Its easy to add a 10 or 14 oz weight, I have one of each. This, the throttle, and the map switch make this one of the most versitle bikes out there.
I have a heavy ignition as well, but it lives on the shelf not in the bike. Too heavy for a 250 IMO. Beleive me I ride some VERY gnarly rocky terrain, and the bike is perfect with a weight and G2 throttle w/#200 cam. Still can snap the front up over a log at will with no clutch, and it never stalls. Thats what I don't like about big heavy flywheels, you loose that ability to a point.
Set up like this, with fine tuned suspension and a Mitas trials tire, its the most awesome bike I've ever ridden in the rocks.