Troubleshooting "from all angles" - iPod Classic 6g with microSD cards

[GreyBeast]

Just a field report: for testing purposes, I built an iPod 6g with an iFlash Dual adapter and a 16GB Sandisk Ultra SDHC card. I had Rockbox on that iPod before and did not restore it after installing the adapter. When connecting to my PC, USB bootloader mode (?) (didn't know such thing exists) appeared and I just formatted the card with guiformat.exe. Then I put a fresh Rockbox build on it and Rockbox started right away. Then I transferred 10 GB of music with Rockbox. Everything went fine and after some hours of using, I couldn't find any corrupted files.

Could it be, that it is rather the type of card than the adapter that is causing the problems?

To those with corrupted files after transferring with Rockbox: what is roughly the amount of corrupted files? Every file, or every second one, or fewer?

Much, much, much fewer than every second one.

Sometimes it takes 30 seconds into the file transfer for files to hang, others times you can transfer 10GB in one go and nothing happens. It doesn't seem like there's a regular pattern.
Also, I don't think it has anything to do with what program you format your storage with. I tried all kinds of different ones, and they all had the same results.

It looks like that leaves two options:

It may well be the type of card used. The adapater manufacturer lists "compatible" cards, as reported by card users. Yet, since there are so many different manufacturers of sd cards, and I can't imagine there's MILLIONS of adapter users out there to report back, I'm not entirely sure it's my sd cards that aren't working correctly, as they weren't "cheap/no name". 128bg sd cards are (still) costly, let alone four of them. I'm not (yet) willing to spend another big sum on "compatible" ones, just to confirm that wasn't the issue.

The other option why your setup is working fine could be the simple fact that you only have 16gb of storage. I had the impression that, once you got to about 40% of the four 128gb sd cards filled up, hangings and lags would become MUCH more frequent and much more "catastrophic" in that stoping and restarting file transfer wouldn't do the trick, because you'd have to run a check first to find and repair corrupted files.