is this new bike going to be your only means of transport???...
i think youd be better off "learning motocross and freestyle" on a cheaper bike....youll be falling off a lot! dont think buying a road bike that youre going to use on the road and then use at a motocross track is a good idea....the bikes get trashed quickly, and youll be forever maintaining it...youll also need a set of spare wheels and tyres, as on the track youll run full on MX knobblies, and they will last about 200 miles on the road if youre lucky....

buy an older MX bike and a bike for the road, but i wouldnt suggest that you should use one for both.....

maybe buy one for the road and use it for a bit of green laning, but not road and mx.........

as for the differences, the EXC will have a heavier flywheel to help generate power for lights and this also helps tame the motors power delivery slightly, the power will be less of a hit, and be much more tractible low down. the 2 mm smaller carb will also retreive some midrange, although slightly at the expense of top end power.

jaydee.