i have a blackhawk (size 3) for my model 38. it has a strip that keeps it secure in the pocket when the gun is drawn. it's not a molded holster, and it's somewhat on the thick side, but it cushions the gun.
I returned back the desantis nemesis and got a mika. I cannot stress how unbelievably awesome the mika is. Doesn't look like a novel in my pocket and is bloody glued to the pocket on draw. I love it.
There is a slight point on the upper edge of the holster that catches on the inside of your pocket when you draw. The holster always stays put. It's also contoured to for whichever side you carry on to aid concealability, but the downside is you can't switch between pockets with the same holster.