DanP:
As others have pointed out, hammerless revolvers do have a hammer -- it's just internal. I know of no reason why you would think a hammerless revolver would be more likely to misfire than one with a hammer. I'd argue that in terms of reliability, the hammerless would be more reliable since the lack of a hammer opening prevents lint and other crud from getting inside the action. It also prevents your coat from getting caught in the hammer (and thus possibly causing a misfire) if you have to fire from inside your coat pocket.
Snagging really is an issue for a small snubbie, particularly if you are carrying it in the front pocket of your jeans. If they'll let you at a gun store, take everything out of your pants pocket. Then try putting the gun in your pants pocket and then drawing it back out. It's easier without a hammer. Note, there is a technique for drawing a gun with a hammer from your pocket -- put your thumb on the hammer spur as you draw. Your thumb will guide the material around the hammer, thus preventing the hammer from snagging. But you'd best make sure you don't push down too hard with your thumb -- having a cocked revolver in your pocket would be rather more excitement than I'd care for.
The downside of a hammerless revolver is that you can't shoot it SA. S&W used to make a snubbie with a shrouded hammer (just the nub of the hammer was accessible above the shroud). That design allowed you to cock it, but still provided protection from snagging.
For pocket carry, I prefer hammerless or shrouded hammer. For belt carry, I prefer to have a hammer. YMMV.
M1911
