Someone with a 28" draw and 6" brace will have a 22" powerstroke. I've got a 33.5" draw and shoot an 8" brace for a 25.5" power stroke. My arrow is being powered by the string for an extra 3.5", but that's also an extra 3.5" of travel time for any torque I put on the bow to affect the arrow's flight path.

The longer the powerstroke, the more energy you put in the arrow. But also, the better your form has to be to maintain accuracy.