I have both and really seem to shoot the Ultra better. From a bench and when my elderly eyes are haveing a good day, they seem about equal. With ball ammo they both will go close to two inches if I'm working right. But for offhand shooting I do better with the smaller gun.
I'm 6' and have average sized hands and don't have any problem with the shorter grip.
For IWB carry the barrel length makes little difference in concealability. I'm scrawny and the extra .4 inches off the grip does make a difference.
Barrel length does have an effect on velocity. I've read differing accounts that rate the loss going to shorter barrels at 30 to 50 fps. However, as M16 says, every gun is an individual and some shorter barreled guns will match the velocity attained in another gun with a slightly longer barrel with a given lot of ammo.
Interestingly enough I recently read an article in one of the gun rags where the author took a number of modern high performance defense rounds and did penatration/expansion test with different barrel lengths. His conclusion was that for close range the barrel length made little difference in the performance of the bullet.
I'd say go with the one you like the best.