I often carry a Ruger Bisley Vaquero, 4 5/8 barrel, chambered in .45 Colt. I use Bob Mernickle's exellent PS6SA holster, on a heavy belt. This holster rides high, and has a cut out on the front to faclitate your draw.
The load I have been using is a 250 grain LSWC over Unique powder. Recently, I have been trying the Hornady 230 grain HP/STX with Blue Dot. This load is very accurate, clocks right at 1200 fps, and in the heavy Ruger, is easy to control. It is not difficult to clear the holster, and hit a 10 yard target, twice, in less than three seconds. (and still have 4 rounds if needed)
Most of the time, I carry a Custom Colt Commander, or a S&W Model 65, but I have no problem at all, with relying on my Single Action Bisley.
Hey, its always been about your ability to shoot, and yes, your willingness to actually pull the trigger on someone. Mind set is more important that what you carry.