Because the limbs rest on your hand with a reverse grip rather than 1 1/2 to 2 inches in front of your hand with a standard grip riser, it's a little harder to torque the bow (side to side), or put another way, the bow is a little less sensitive to side to side torque.
Because the limbs are closer to the hand, they do not flex as much/far as the limbs of a standard grip bow at the same draw length. I think this permits a somewhat shorter bow for a given draw length. For example a 66-inch reverse handle ASL instead of a 68-inch ASL with a standard grip for a 28-inch draw.
Because the limbs don't flex as much/far, they may need to be constructed with a little more early load. This may or may not affect the smoothness of the draw and speed. If so, I haven't noticed. I just like the feel of a reverse handle, and I do drop down two inches in bow length with my reverse handle bows vs my standard grip longbows.
That's about all I can come up with, and my observations apply to ASLs only. R/D longbows and hybrids have much greater variations in riser and limb design that can overshadows these features.