Yah it kinda sucks that they didn't use the standard 8 x 16 x 5 but I'll get over it.

Serpent vs Evo
 

I have been racing he St-rr. Cadillac is the best word to describe it. It is very docile and easy to drive. Steers great on and off power but doesn't feel edgy. It kind of reminds me of the difference between losi and associated 1/10 scale. The losi is more forgiving and easier to drive. The associated is edgy and responsive which can enhance a good driver but make a average driver worse. As far as the evo goes...it is an st-rr with new "straight cut ring and pinion gears fr and rr. New bulkhead housings "d" version. The d is a stiffer material. The were getting flex and blowing the gears. They went with a straight cut (vs spiral) because they are more durable (arguably) and forgiving (not as smooth). My opinion is that the bulkheads were the problem. The evo comes with captured hinge pins. The old e-rings used to pop off a lot. New body, gun metal anodizing rather than purple and a mp9 wing stay and wing. All of the upgrades are for looks and durability/functionality. Much need upgrades. I agree that Kyosho has gotton out of control with their prices. I have already done the math and it is cheaper and makes more sense (all new parts) to buy the new kit rather than upgrade the old one. Hope this helps.