The gun is there to serve me, not the other way around.
That's not to say that I'm totally unwilling to change how I dress to carry, but there are limits. I draw the line at buying a different set of clothes just for carry. In practice, that doesn't mean I can't ever carry a full-sized pistol, at all, but it does mean that there are some situations where I can't conceal a full-sized pistol.
That said, my compact pistol holds 8 rounds and it has a long enough grip and sight radius that I can shoot it very well. I figure if I can hold a 10 shot group under 5" at 25 yards with a pistol, it will do for most anything a person with a pistol would reasonably be expected to do.
I think the key is shooting your carry pistol to determine your capability with it. If you find that you can't shoot it well enough to satisfy you, then maybe it's time to consider whether or not you want to change your mode of dress to allow concealing something that might be easier to shoot.
In my experience, once you get above .380ACP, most people will want all three fingers on the grip of the gun to properly manage recoil and to provide adequate "shootability". Going shorter than that on the grip will result in a noticeable handicap--and also hurt you in the capacity department. As the caliber goes down, so does recoil, and a two-finger grip can work ok in those situations--although the shorter grip is still going to cost you capacity.