I'll add another two cents Get an all steel model, because your BUG needs to be shot as much if not more than your primary. Yes to the revolver, as you may have to shoot through a garment. Do that with a Semiauto, an you now have a very expensive singleshot semiauto. Back to the all steel revolver, your going to want to shoot it, your going to need to shoot it, an your going to want to shoot your defensive load to know where its going to hit at different distances(Yes they can be accurate out to 25yds an beyond). Oh yeah, get yourself some quality gear, your gonna drop a few bills on the gun, don't skimp on the gear!!!!!!!!
I've had a 640-1 and a 442 for years. I used to shoot them side by side (only with defensive loads) every time I went to the range with a primary semi-auto. I used the same ammo in them (.38+P) and admit the 442 wasn't quite as comfortable as the 640. However, I gradually quit shooting the 640 and eventually it became relegated to a bedside gun for my wife. Why? Because when I put one on in the morning it was always the lighter 442 and I shot it just as good as the 640. I haven't worn it out yet and if I do, I'll just buy another one.