Too heavy? Maybe - depends on what you're comparing too, how you ride, where you ride, and so on. It's not a lot heavier than the 4-stroke mx bikes. If you are commuting at any sort of speed, I'd suggest getting another set of rims and tires. The knobbies aren't great on hard top, and the rim lock provides a pretty rough ride if you're over 60 mph. Dyna beads help a lot though.
Too powerful? Not often a racer will complain about that! Certainly lots of power on tap. I find it very smooth and controllable though. If you're serious about the racing, I'd get the rekluse put in. That will save you a bunch of energy on technical terrain. If you do anything with high hp requirements like ice racing, dune riding or snow biking, this bike will out-pull any 450 mx. Just keep in mind that if you're not in good shape or not a good rider, this bike will tire you out pretty quick compared to a 250!