I have been carrying a model 637 every day now for the last seven years. I assumed the hammer would get in the way and I would trim the spur with Dremel moto-tool and cut-off wheel . Old school modification. Guess what....the spur doesn't get in the way. People tend to make a problem of it...it's not a problem. I like to have the option to shoot single or double action.
Before you buy, if at all possible, try shooting both or at least dry firing both, then decide.
Gary