The B is actually a second series of the TCP, it's not really an indicator of the color of the slide. The A models had a problem with chambering rounds in some cases, so there was a redesign of the feed ramp to aid in first round chambering.
I've had my TCP for a couple months and I've put about 120 rounds through it. The edges of the slide are already starting to show wear. It's a blued C model. It shoots fine but I can't say I'm impressed with the fit and finish.
I am not sure that dura coat is really much more resistive tio wear than regular bluing?
and you need to make sure that you don't cause problems with tight tolerance areas like the rails and frame fit.
the finish on the 738 is about like any other lower priced weapon, a little care goes a long way, course pretty don't make for a better operating pistol only a prettier one.
a pocket pistol is normally full of lint and cat hair anyway, so thats not a lot to look at!-LOL