If you get the revolver, due to the gap between the cylinder and the barrel, if you were to submerge the firearm in water and pull it out, the water would immediately drain out and discharging the firearm at that point would not result in an exploded barrel due to barrel obstruction (water).
It will fire when dirty, wet, greasy, etc.
Revolvers have the balls to work in hell. Not many Autos these days can say the same thing. Don't buy a Rossi, or Charter Arms. I make a habit to avoid Taurus too, but that's mostly irrational.
I've heard tales of polymer framed revolvers, which I would imagine would be hard to notice in the pocket while running. (as in, your leg/nuts won't be smacked relentlessly by a heavy piece of metal, because it's a lightweight piece of plastic instead.)
On that note, I wear a 1911 in a Smart Carry, and occasionally run with it. No problems in that regard, and could recommend the same system to you. Smart Carry can be worn butt naked, or will successfully conceal a slim-line 1911 in a pair of comfortably fitting pants. (not excessively loose)
(or any other firearm)
Kel-Tec PF9s are pretty damn light weight, though the trigger is a royal piece of shit. The one I got for my girl has worked very well, though. So has the Kel-Tec p32.
@Geeza - Not everyone shooting at you is a cop or a gang member participating in "gang initiations" or whatever it is that gang members do
@Geeza again - Not every interested hostile party is going to run after you.. People have cars and other shit white people came up with.