I understand what you're trying to do, but that just encourages people to make slim, nimble, speedblitz characters as opposed to larger and more powerful bruisers. Generally, that ends up pissing off a lot of people and creates pissing contests as to who is faster and who reacted first. I planned on bringing a bigger guy in, so I'm sure you can understand where that could be an issue. 

Another problem from that is... if I have a guy who is like 6'10" 325lbs if thick muscle... and someone who's like 5'8" 140lbs of speediness... My guy could likely tank repeated blows from them. That would piss THEM off as much as me not being able to hit would piss ME off, you know?