I owned the 2 1/4" version (that was what the store had when I was hot to buy; it wasn't what I wanted), and wished it was the 3 1/16" version. The 2" was just a little too heavy and bulky for discrete front pocket carry (tho I tried it a couple of times) anyway, and other types of carry would not have been affected by the longer barrel.
Performance wise, the magnum loads would have really appreciated more tube to "get their legs under them." I disagree that with those who feel the extra bbl wouldn't make much difference in velocity - search around and look at chrono readings people have posted over the years for .357s: they really begin to come into their own in a 4" bbl, but 3" moves the bullets out considerably quicker than 2".
Leather? I don't think you can find a pocket holster for the 3", but DeSantis and others make them for the short tube. Most other holsters work for the longer bbl (tho you may have stainless showing out the bottom!). Accuracy? I'm not sure it would make a heck of a lot of difference if you practiced, but the longer sighting plane and increased weight up front would likely help somewhat. Not enough that this should be a deciding factor.
Loved the SP-101. It was great fun to shoot with light .38 handloads, and had decent OOMPH with the hot stuff. Loved the factory grips, loved the smooth trigger. Trigger was heavy beyond belief, but Ruger tells you to dry-fire the thing to wear it in (it works, and it's good practice). The only reason I got rid of it (sold for a great price to a good friend) is that I had just bought a 940 that filled the niche I had in mind better.
I would buy another SP-101 (preferably with a 3" tube, but that's your call) in a heartbeat. I envy you, priv8ter! Have fun with whichever you select!