Some great advise here. I'll throw out an idea you may have not considered... a M638.

It would give you the DA/SA cockable hammer of the M649, and the light Airweight frame of the M642. The -2 and latter versions can handle all the +P .38 Spl you'd care to shoot.

The older pre-lock guns (the -2's) were very well made (if you can find one). I'd say equivalent to current PC/Pro guns on smoothness, finish, and fitting.

__________________
~ S&W aficionado in training ~