Hi Mike, By the way are you the Mike that was here in Dunedin this winter? There can't be too many guys named Mike that live in Niagara with a H21.
While not class legal(shouldn't be a problem)you would probably cut the weight by half at least. Reducing weight aloft is a good thing not to mention having to raise it.
As far as costs go I was looking at the Mystere parts list and the Viper has a carbon mast listed and I think it was around $3700. That mast is 34ft. tall. I'm not sure if that is in US funds or Canadian. You probably know if that's in Canadian funds you can deduct about a third from that.
Mike