Btw, is it possible to get rid of the Apple operating system only running the Rockbox?
Maybe have a look over at the
freemyipod project...
Like the Rockbox bootloader though (and this is pretty much the only similarity it shares with the Rockbox bootloader other than being able to boot Rockbox), it is still capable of booting the Apple firmware image, but installation also offers the (optional) choice of completely un-installing the firmware partition to recover (a fairly trivial) amount of space.
The freemyipod project and the Rockbox bootloader should be looked at as being completely separate, and freemyipod tools/firmware is aimed at a more advanced user.
Bricking risk is incredibly minimal, but it is possible to use the tools to do some very, very silly things that *can* brick your iPod, but only if you made an effort to specifically ignore instruction or not to seek it in the first place

It may be worth your while to drop in to their IRC channel over at #freemyipod on Freenode to get your feet wet discussing the pros and cons before you jump in the deep end.
[St.]