A gun and its holster add the same "thickness" to the side of your body, whether they're inside or outside the waistband (assuming the same type of holster construction.) IWB tends to present a smoother contour than OWB if your cover garment is the least bit tight, but if it's loose there isn't much difference. (My cover garments are usually Hawaiian shirts in the warm and cotton sweaters in the cool/cold.) I carried IWB for many years, but last year got a Lobo enhanced pancake holster and one of his solid belts, and now much prefer OWB carry, with the gun at about 4 o'clock. The butt stays solidly against my side, pretty much no matter how I stretch or bend, and I don't think it prints any worse than it did with an IWB holster.

I have both 2" and 3" K frames with a good holster and belt, and agree with others that they're a LOT to carry concealed on a regular basis. So if you're only going to have one gun, and you want to shoot it a lot, I'd look at the steel J frames. SOME people seem to tolerate the recoil of alloy J frames well, just as some claim to not mind shooting 357 Magnums out of J frames, but for most folks it will be unpleasant enough that they won't want to shoot very much. You can make an alloy J frame fairly tolerable to shoot by putting a big cushy Pachmayr Decelerator grip on it, but that grip is VERY hard to conceal so you'll want a "regular" grip for daily carry. But then the gun doesn't draw, present and shoot the same with a giant soft grip as it will with a smaller one, so your practice won't be as effective.

Even though I only carry 38 Special ammo, I prefer the magnum J frame (I carry a 640-1 but would be just as happy with a 649-3 - I don't like locks) for the slightly greater weight and sight radius, but mostly for the longer ejector rod, which seems to make extraction of 38 Special cases more reliable than with the 38 Special-only guns (of which I have several.)