I took the E-5 along with my Canon EOS 7D to shoot the Red Bull Rampage mountain bike freeride competition in Southern Utah. Red Bull Rampage is arguably the top mountain bike freeride event in the world. Once thing is for sure - there's nothing else remotely like it. It also separates the men from the boys as far as photography goes. You have to be prepared, fit, have good technique and be willing to hustle to get good photos. You can't just sit there and hope something will happen in front of you.
I ended up mostly using the E-5 and 12-60mm lens to compliment my 7D with 70-200mm. For an event like this it's best to have two cameras ready - one with a telephoto and one with a wide-angle lens. I haven't had a chance to look at the RAW files yet but I didn't have any serious problems with the E-5 other than the JPEGs seeming to be a bit oversaturated in the red channel. It never did anything weird and the 5 FPS burst rate works well for big sequences. I think 6 FPS would have been better but 5 is fine, as you can see from the sequence here. When I figure out what to do to get at the RAW files I'll find out if there's a serious red problem. So far I've been able to correct it in post-processing.