They don't need as much power as some other components. It's not really a good basis for comparison, anyway.
General rule of thumb:
750w = twice as loud as 75w (10x the input power).
100w = dang near the same as 75w (negligent difference).
It's all in the install and the capability of the product.
I'd put the Type X Vifa made mids, tweets, and their awesome psv-xovers up against just about anything in the same price range (maybe even more expensive) and be willing to bet they would sound more natural/less colored in same type installations.