I was in your situation, a little while ago. I wanted the same brand and same caliber. For a year and a half I only had two guns that I'd carry. Some people prefer a mastery of one type. The problems arise when you shoot different guns and do not practice enough to get good with any one of them. The double action trigger of a revolver is a different feel from a double action of a DA/SA pistol (I.e. Sig Sauer or H&K) from a Striker fire pistol. Configurations of sights vary and acquisition is quite different. Lastly, you have to deal with safeties or lack thereof. One gun I don't carry is a Beretta because the action to disengage the safety is opposite of my 1911s and H&K.
I own a lot of different pistol types. I shoot some exceedingly well, some above the average, and only a couple at a level above minimum competency.
The key that has helped me is taking a gun and dry firing it frequently, learning the nuances of the trigger and how to speed load it. Hence, I can take any gun off the shelf and shoot it well (except calibers that I have an aversion to shooting like 44 Magnum, 500 S&W, etc).
As long as you invest the time to learning the various guns, you should have no issue.
However, carrying a gun adds to additional levels of training, shooting from various positions, drawing from concealment, etc. in this case, the fewer variables, the fewer issues you will have when it is needed to draw. I use the same holster brand/type (Kydex/leather) for each, same position, except for my P238, a backup.
My carry guns:
Ed Brown Special Forces
I have carried revolvers such as a S&W 627 Pro Series or Colt Python but the frame size is impractical except for open carry. However, I'd resort to these more for home defense.
Last edited by CDR_Glock; September 19, 2012 at 09:04 PM.