I've got the 442 (no internal lock). I would recommend it over the 637 for concealed carry since the hammer is internal and there won't be any snagging on a draw—possibly from a pocket, which is where this gun shines. The 442 also lets you get a higher grip on the back strap, making it a bit more controllable.
They are more accurate than anyone can shoot them. I've shot a cloverleaf (sometimes I get lucky) at about 25', resting, and staging the trigger—not that comes close to how this would ever be employed.
It's got about a 10–12 lb. trigger which if you're not used to revolvers will be a bear for a while. If you get proficient with the trigger, it will most likely make you a better shooter with an auto.
+1 on the Nyclad comment. I'd rather have five accurate shots than the extra fire and recoil of the +P rounds. I would highly recommend getting your hands on one (rent or a bug a friend) and shoot it a bit.
If you've got big hands you might find the trigger reach a bit too short.