They certainly serve a purpose and work in their dedicated way. I do not care for them as I do not like having a revolver that can not be thumbcocked for single-action fire.
1) I agree that single action is nice for a range gun. But I just don't see it as a requirement for a CCW gun. Everybody wants to quote the stats that the "average gunfight" sees 2.7 rounds fired and takes place at less than 7 yards. How does single action capability fit into that? Even worse, the "average" criminal attack takes place in a very short period of time and in dim light. This is not the conditions you need for "precision aimed fire." It would be a _very_ rare civilian shooting where a precise shot in single action would be the appropriate action. It is _far_ more likely that the civilian will cock the hammer "because he does that at the range" and then fire a shot when he didn't mean to do so. Or at least that is what the attorney for the deceased will say at the civil trial.
2) And single action fire doesn't have to be any better than aimed double action fire anyway. If we went to the range and got out the sandbags and 25 yard targets, I'm willing to bet my five shot groups out of my 6" Ruger Security Six will be the _exact_ same in single or double action. I've used that double action thousands of times and "the feel" is very well known to my trigger finger and brain. I've made some amazing shots with that revolver in double action even with single hand unsupported. I even won a small bet one time by cleaning the hostage targets we had set up at 50 feet with it standing, one hand unsupported, _weak hand._
DA is all you need for personal defense. It is safer under stress. Single action can actually be a liability. And DA is capable of wonderful accuracy if you spend the time mastering it.
Gregg