Sean,
Grip style and hand position are really personal choices. I would suggest that the high wrist is physically weaker than a low wrist. Think about doing pushups. If you were to do them on your knuckles with a straight wrist, you have the added stress of keeping your wrist straight. If you do the pushups on flat hands (palms flat on the floor) you take the instability of the wrist out of the equation.
Since you have shot and gotten used to the high wrist, you are used to it and the low wrist feels strange and you are not confident with it. IF you are looking to change your grip, take a look at a thread here on the "shooter's form forum" called "grip question." (do a search and it'll come up) I posted some pictures of a grip that will work for any style bow grip. This grip CAN allow the shooter to shoot any style or contour bow grip without worrying about whether it is high or low.
I'd also suggest that the high wrist grip tries to place the pivot point of the bow and the pressure point at the same place in your hand (the web between your thumb and index finger. Most bows have the pressure point designed to be below the pivot point and this is especially true for straight grip longbows (think Hill style bows).
As with ANY shooting style change, just trying it during one shooting session will NOT give you a fair idea of whether it is a good change or not. You have to stay with it for a good while.