QUOTE(kornchild2002 @ Feb 22 2008, 17:08)

Personal feelings aside, I feel that Rockbox for the iPod isn't really worth it. Rockbox still doesn't run as efficiently as Apple's firmware. I think someone did tests (not here) and found that their 20 hour rated 5G 60GB iPod played -V 4 encoded mp3's for about 12 hours before shutting down yet it was able to easily get about 22 hours using the iPod's firmware. So that right there is enough to stop me from using Rockbox given that I normally use my iPod for about 18 hours before I can recharge it. That and you lose video support with Rockbox (at least that is what I heard back when I used my 5G 60GB iPod, I now have a 16GB iPod touch).
That was probably me - as I am the only one I have ever found who has done detailed and documented runtime tests comparing Rockbox and the Original firmware under very controlled conditions. Those also appear to be the numbers (11.5 and 21.75) I posted in the IpodRuntime Rockbox wiki page testing the runtime effects the up-and-coming coprocessor enablement (and 64MB RAM enablement) would have.
That is also old news. Rockbox now easily archives 80% of Apple firmware runtime, gaining by leaps and bounds.
You also do not lose video support. Rockbox dual boots with the Apple firmware, you can easily boot into the original OS if you want H.264 playback, or you can use Rockbox's (developing) MPEG-1/2 player. Your choice.
EDIT: Pruned irrelevant parts of quote.