Can't shoot small guns as well...
... well, maybe... For me, a true, pocket weight revolver (S&W Airweight or one of the Scandiums) would suffer, compared to the 9's, not only in terms of total ammo capacity, but potential rate of fire.
I can shoot my SP101 very accurately. However, I can't get an accurate rate of fire with it that would even begin to approach the effective rate of fire I can get out of my Beretta Centurion, or even Sig P239. At 7 yards, from the Beretta, I can put 15 rounds in the sweet spot about as fast as I can put 5 .357's from the SP. In the same time, I could put 8 or 9 from the Sig, and be well into the reload.
If the SP's CrimsonTrace is activated, I can bring the fire rate up significantly over iron sight aimed fire, but it still doesn't match the 9mm's. And bear in mind, most consider the SP101 to be too bulky for pocket carry.
Revolvers can be shot quickly and accurately, of course. I can shoot the GP100 nearly as rapidly as my 9's, but it's not exactly a pocket pistol. Frankly, I am not confident in my ability to conceal it under anything less than a jacket.