I bought a h120 a while ago and, after some reservations, made the plunge and installed Rockbox. After that I only ever used the iRiver firmware for recording, which Rockbox didn't have good support for back then.
When I got my h340 a couple of days ago the first thing I did was install Rockbox. In fact, I haven't even explored the iRiver firmware at all.
Answer is yes, you can uninstall rockbox. The simple way would be to simply delete the .rockbox folder and the rockbox.iriver file from the root of your player. From then on it will boot into the iRiver firmware everytime. To completely remove it, you should download the firmware from the iRiver site and flash your player again.
Why you'd want to do that is beyond me.
