The two Cateye CS-1000 Cyclosimulator we've had are good for 1,400W+ before burning rubber and if you crank the roller really hard, maybe more. For some that is not enough, but it is higher than anything you set a bike on.

I agree with your track bike/hill/real bike needed for max power. But - as I posted - for that I think gym is as good. Hard to beat a stack of weights on a leg press for max effort.