It's certainly not a class for an Ao100 game, you'd burn through too much ammo.
As for regular games?
Well, it's certainly a lot more effective then I assessed it. I didn't see that it didn't block shottyman which I thought would have been a given because that essentially turns it into Gun Kata 2.0 for shotguns.
You pass up TaN, SoB, and Whizkid.
Whizkid is a good pick if you have lots of perks - such as on a 100% UV/N! game. You also kinda need to be kinda lucky for it to pay off, so it's not really a good or a bad block, just kinda neutral.
Passing up SoB on shotguns isn't really a big deal, it'd just mitigate one point of armor at most.
Passing up TaN would be more of a tossup but you have Dodgemaster. Having badass for those revs and mancubuses would have been great but hopefully you can just corner shoot them.
So you don't really lose too much if you're playing it as a shotgun build.
As for the master trait itself? I think that the strength is also the weakness. You need to be REALLY careful with your movement - Say that you spawn next to an imp and a barrel (It's happened to me before!) You shoot the imp, barrel explodes, you die. Having Juggler does help but you would need to keep an empty hand or a chainsaw or something in that situation - lest you shoot the monster next to you with that handy dandy rocket launcher.
You basically need to be very aware of the situation.
Does that mean it's a bad build? No, that's just my critique of it, and i'm actually going to give it a shot right now.
Well done on the run by the way.