Personally, I would never carry any gun which has a magazine disconnect, and the Ruger SR9 does. If a BG gets close and gets his hands around yours, and forces the magazine to disconnect, the gun is now as useful as a brick, even if there is one int he pipe.
One of the worst safety features ever IMO.
Forgot to add, my necessities for a carry gun are:
-Light trigger (5 lbs or so)
-Single stack (not too think for the hands)
-Single action (no heavy or squishy trigger)
-No magazine disconnect (want a gun, not a brick)
-.45 ACP (a proven fight stopper)
-No more than 28 ounces
FWIW, my carry gun is a Kimber Crimson Ultra.