Mike, I'm close to 6', but not there anymore :( I shortened my string quite a bit, but found the angle of the string was pulling the block back down the limb if I did not keep a lot of outward pressure on it. I put a new, full length string on and found if I spread my feet fairly wide, the angle of the string is nearly straight down and doesn't slip back down the limb.
Guys may need to shorten the string, depending on height, but before cutting it back, I'd suggest spreading the feet a shoulder's width apart and see if that works. "Measure twice; cut once".