Looks like I'm about 5 years late to this party, but...
I read recently that for those of us with failing eyesight, in a certain respect we can get better accuracy with SHORTER barrels. Reason being that as you focus on the front sight, the further the rear sight is from it the blurrier it becomes. Therefore, the shorter the distance between the sights the sharper you're going to see them, ergo potentially better accuracy.
Once this idea got into my head, yeah I notice that I can line up my 4 3/4" revolvers a little better than my 7 1/2". I feel like I can see the sights better on the 4 3/4" than the 5 1/2", but I don't really notice any practical difference.