+1 on the Hogue Monogrip, and thank you for the excuse to post this photo again! This is my 2.25" SP101 dumping a Magnum round. (You only see the awesome circle of fire in a high speed photo; with the naked eye you just see an awesome orange blur.)
Regarding the DA/SA hammer, here's an occasional rant of mine. Purely my opinion, but don't do it. I consider my SP101 a defensive handgun. Defensive revolver shooting is DA shooting, so that's what you want to get good at. If your gun's DA only, then you'll actually practice DA shooting, and you'll find you can get pretty darn accurate (Google "staging revolver trigger"). Hammer spurs are for cowboy guns!