I have an EVO 4G, came form a palm pre. I just rooted and flashed CM6 labor day! It was a PIA, (newb) but I got it done with videos, tutorials, and a lot of trial and error.
THAT said, EVO 4G stock, I rather have my Pre. It was just that much more intuitive, and easier to manage things. The OS had me sold. But after rooting the damn thing, and flashing CM6, I couldn't understand why I didn't do it earlier, or be scared of it. Sure, I lost 4G, but it kills the battery anyways, and the 30 FPS made the phone feel like a snail... now, with it uncapped, WOW! the touch response is Insanely faster (though still trails behind all mighty apple) but everything scrolls faster, the responses for things opening is MUCH quicker. I like this aspect of it!
Anyways, if they had an awesome hardware for the palm pre, with 60fps+ UI, I'm sold. Goodbye EVO in a heartbeat.