Love them humpbacks
Like most of the other guys, I love them humpbacks. My wife carries a 638, her truck gun is a 649, and my motorcycle / walk the dog gun is a 639. I suggest getting one with the 2-1/8" barrel because it has the "full length" ejector rod, which the 1-7/8" versions do not. I do not have any with the internal lock - a testament to PC (not Performance Center) insanity.
I load them all with the FBI load - 158 gr. SWCHP at about 925 FPS. Buffalo Bore carries this in regular and extra crispy. The +P's hurt to shoot, but will clock over 1000. The regular loads do just fine. Supposedly the FBI load has the "stopping power" of .45 hardball. Add a tritium Big Dot and you are good to go. Shot placement and control. The market may not like them, but we love 'em.
By having the same carry gun, we can trade speed loaders if needed, and if I get shot too badly, she can pick up my gun and continue the fight - not a pleasant thought, but a necessary one.
Semper Fi.