Evilnick, you and RockBox have something in common. You lack maturity. At least you responded. Your answers are mostly wrong, though.
An axiom of software design is to create something so completely obvious that no manual is needed. You see a baseball, and you know what to do. Another axiom is to never expect users to read the manual. A third is to keep your software simple. Resist the urge toward featuritis / f. creep. Not an axiom, but a good practice, is to write documentation that is clear and complete, from the perspective of users.
RockBox's manual is fairly clear and complete, but that's about the best part of it. RB is jam-packed with features upon features. You have to do "long presses" of buttons to do actions. Sometimes, one button is the intuitive choice, and yet another is what you must use (e.g., the select button is used to pause recording, instead of the pause button). There are very long sequences of menu options that you must scroll through. It's a mess. A fun, capable mess, but a mess.
That's all UI stuff. My most important gripes here relate to the installation process, and what it did to my MP3 player.
(A) Installing RB transformed/moved my files & folders. They were MP3 files, in \MUSIC\(artist)\(album name)\. After installing RB, the MP3 content was stored in *.DAT files, in folders like a hidden \SYSTEM\MTPCONTENT\0\3\A\ folder (and about half of that content was added using MSC). The folder structure was gone. File and folder names were mysterious.
(B) To get RockBox to see any music, I had to add more MP3 files, which caused dupes. I quickly ran out of space, and needed to end the duplication.
(C) Would I be able to uninstall RockBox, hoping Sansa would continue to read those DAT files? (As it turned out, no.) If it couldn't or I wanted to keep RB, which of the *.DAT garbage could I safely delete?
Here's what led to this, in case an RB developer is more open-minded, and willing to benefit.
Stage 1: Wife gets Sansa c240 player, pre-set to MTP. Some songs added via MSC. Some via MTP.
2: Later, I inherit player. Switch to MSC. All *.MP3 files, in the \MUSIC\ folder.
3: Upgrade to Sansa firmware 01.01.07. Oddly, this changes USB settings. No MTP option! Just Autodetect and MSC remain. I'd been using MSC mode, exclusively, yet after the fw upgrade, it's set to auto-detect! Does it matter, since MTP is gone? It should autodetect and be forced to pick the only option, MSC. Right? (Wrong.)
4: Install Rockbox with util. Change "General Settings: File View: Show Files" to "Supported." As the manual states, that setting does
not show hidden folders or anything that begins with "." (dot). So, in the Files option, all one can do is see that VERSION (.TXT) exists,
view it or return to the main menu.
Issue: One cannot delete, rename, move or copy the file(s). One cannot navigate to any other
folder, or even know the directory name (\ , i.e., root). One cannot set the default folder to anything else. When you go into "Files," you
see the root, but you don't know it's the root, unless you use Explorer.
Now, from Windows Explorer I find the (hidden) \MUSIC\ folder empty! (No mention of this in the manual, and SansaFAQ online is misleading.) If
I reboot into the original firmware, then I can see and play my songs, but zero music in RockBox. The original music is stored in \SYSTEM
\MTPCONTENT\0\.. subfolders, in 00000*.DAT files. The folder structure has 1-byte-named folders; many are empty. Many files are empty, too, or
only 1b long. Those with songs are all in ..\0\1\F, ..\0\2\0 - F, or ..\0\3\0 - F folders. File dates for the song files are all from mid-
November 1985, for some reason. (1985 pre-dates LAME 3.93, which I used to grab the music.)
5: Copy some MP3 files to the (hidden) \MUSIC\ folder. Now RB can play the files I copied. It helps to unhide the \MUSIC\ folder. It
quickly runs out of disk space, though, due to all the duplication with the *.DAT files. If I reboot into the OF, then I see all my original
(*.DAT) music, plus any dupes in the \MUSIC\ folder.
6: Change "Show Files" to "View All." Files menu is navigable now, despite hidden folders. I can go to \SYSTEM\MTPCONTENT\0\3\B\, and
see 000003B3.DAT. (A file viewer from Windows shows that it has LAME 3.93 content from my album. It can't be played.)
So, my old folders are not on the player -- no longer organized by artist and album. My old MP3 files are gone, too. So I can't copy them,
edit them in Audacity, delete them and easily know what I'm deleting, etc.
7: Delete the files from \MUSIC\, and reboot into Sansa OF. In Stages 5 and 6, there was my full collection, and duplicates of many.
Deleting these files
ought to just delete the duplicates, for the OF. Nope. Now, Sansa OF can't see any songs. Doesn't matter if
\MUSIC\ is hidden or not.
8: Re-add the folders/files to \MUSIC\. Will it go back to Stage 6, when RB only sees the copied MP3s in MUSIC, but OF sees all music,
with lots of dupes? Nope. RB and OF see the same thing: only the files in MUSIC. The connection between OF and *.DAT files is broken.
9: Last stage. Backup and delete SYSTEM\MTPCONTENT\ folders from c240 player. Rockbox and Sansa firmware can both use the MP3 files in the MUSIC folder, and there are no dupes, and
plenty of space. Everything is good, except I have to find backups of most of my music, or else re-rip the songs.
***
Did I fail to follow instructions? I had good reason to think I followed them closely, and that the USB was set to MSC. See stage 3. You say it's "impossible" to install RB otherwise. I'm not so sure. On my player, "Autodetect" is close enough to MSC to allow a RB install, but far enough for Windows 7 to treat the c240 differently.
Did I fail to read the manual? Nothing in it or on the rb.org site could have warned me.
Are you skeptical? I'd be. I'll re-test. As I write, I'm changing from MSC to Autodetect. As before (since stage 3), there is no MTP or other option. I'm connecting, and voila, the c240 appears in Portable Devices, with no drive letter. The folders that were hidden in MSC (like PLAYLISTS) are not hidden. The MUSIC folder appears empty! (It should have 6 folders with 9 albums worth of MP3 files.) OK. Now I'm disconnecting, and setting it back to MSC. I'm reconnecting. It gets a drive letter again. The MUSIC, etc. folders are all hidden now, and the MUSIC folder has the 6 artist-subfolders with many album-subfolders and MP3s. Craziness.
Did having the USB set to Autodetect, with MSC as the only other option, cause this installation heartache? And what really caused MTP to
disappear, and Autodetect to act strangely? Again, craziness.
The 2 bugs are not bugs. They are caused by user error/lack of reading the manual.
The manual says nothing about the Presets
Scan and how (on the c240), it counts garbage on almost every frequency as a station. Also, can you delete a preset, except by carefully editing the *.fmr file by hand?
Issue 5: Stuck on Recording screen bug
Not a bug. See http... ...as for leaving the menu, what button does the manual say quits that screen?
Long press of "Power button" (menu, on the c240). This works, but you have to do it just right. Too long and it powers off. Then, power back up, it's back to the recording screen. So, yes, it's too easy for users to get stuck. Long press vs. short is bad enough. Now we have short, medium and long?! OK...
You're surprised that the recording menu is for recording ?
You wrote "recording
menu," yourself. Why the scorn? Any new user might expect a menu with recording options, like to view/play/delete/rename ... especially a Sansa user. We're used to menus!

To see your recordings, you have to leave Recordings and go to Files. To delete or rename, there are more long presses of the select button. Then, multiple presses to confirm. It takes you away from the Files screen, to the main menu. What if you had multiple files to delete? Also, where did RockBox store the recordings? Into a recordings folder, right? Nope. They go into the root directory! Does RockBox distinguish between recordings and MP3s? Nope. Playing <ALL TRACKS> mixes recordings into your play list. You can find ways to exclude them, but how many users are going to want that?
Maybe the RB developers had good reasons for these decisions, but they sure seem odd.
Rockbox can do cool things, but has poor design. It's the poster child for feature creep, and that ruins the UI. Have you ever had to do a "long-press" on your keyboard or mouse to do something?