Here's an excellent thread on strengths & weaknesses of the different manufacturers' DA revolvers in general:
http://www.thefiringline.com/forums/...d.php?t=317876
I bought a new SP101 for about $460 I believe. Bought the Wilson spring kit, downloaded the IBOK on how to polish up the action and installed the reduced power springs, and it is all good.
Much as I love the SP101, I have to admit that the S&W actions are still smoother. For a defense gun, a S&W would be fine. You'd be shooting 38 Specials or 38+P most likely, and Smiths will handle those OK. They'll just shoot loose sooner. The Ruger will never shoot loose.
OWB with an untucked shirt is a better option in my opinion. SP101s are bigger than the S&W J frames, but smaller than the K frames. Kind of big for IWB, unless all your pants are too big already.