You might take a look at the 8 3/8" S&W revolvers. My M57 is my most accurate. I suspect that the sight radius has a lot to do with it as well as a most excellent trigger. I do prefer a 4" for woods bumming, but I have carried the 8 3/8" in a chest rig which I find quite comfortable in the warmer months.
Folks love their 8 3/8" M27....
I do shoot 6" or longer barrels a little better than 4" revolvers. I believe it is a consistancy issue with me.
With the GP-100, I really like the 3" version versus the 4", but either are just fine.
Handled a 5" S&W 686 and just loved it. It was a special run for Bass Pro and I passed. I regret not buying one today.
As far as dry firing a revolver or any gun for that matter in the store..... ask first. If the gun is a collector grade gun, the store may well have an absolute fit if you dry fired it. Generally not a good idea to dry fire 22 revolvers. If I am buying a gun to shoot and I am pretty well sold on getting it (price and so forth), I will almost always dry fire the gun in the store. But I will be past the "just looking" stage at that point.
Dry firing a revolver will mark up the cylinder (drag line) and some folks simply don't want to see a drag line on a new purchase. For a shooter, regardless of being new or used, I have no problem with honest wear.