I actually tried some MaxAmps packs because I read their voltage was so much better, though only for 40 cycles or so. I'm a pretty decent club driver, and I couldn't see any difference in speed or lap times between those and the Orion packs. This was running 13.5 brushless.
What I did notice is that the MaxAmps packs would fail on my charger consistently. One time it would be voltage too low, the next time voltage too high, etc. I had to try about 5 times before it would finally start charging. This happened to multiple packs. The Orion packs have never demonstrated this behavior.
I guess what I'm trying to say is that I'm not convinced that even if a voltage edge is found, it will be enough to sway a bunch of people to use it. With NiMH, there's a very distinct advantage to better packs in certain styles of racing. Whether or not that holds true to the same extent with LiPo will be interesting to see.