The SP101 is a great gun and if you shoot it well, stick with it. IF you decided to go to an auto, check them all out and find the one you are most comfortable with. I have a Beretta . 380 that I like, but it is a smaller, weaker round. New improvements in ammo have made good . 380's, but it's still small. I also have a Springfield XD40. Very good gun, but mine is the 5" Tactical, so it's a little big. They do make a 3" which I would look at. As for caliber, I think the . 38+P+ or . 357 are two of the best, though . 357SIG, . 40S&W, and . 45ACP are right up there. The . 45 is a little harder to get in a concealed mode and still be controllable, but if you like it, go for it.
In the end, wheelguns are MAYBE more reliable, but many of the new autos are dead reliable too. On the other hand, revolvers are an AIM-PULL-GO proposition. Since most of us don't have the opportunity to train in a stressful environment, I stick with my S&W snubbie in . 38. Five pulls, five bangs!
Have fun!