Also, put the trait in perspective: unlike all other masters, Scavenger doesn't block any basic traits, allowing you to apply it to just about any build you want.
This is true, but with it blocking Dualgunner, Berserker
and Triggerhappy, the only weapon specific skill it doesn't block is...Shottyman.
Which isn't incredibly important to the playstyle as those other three skills are anyways, so you can just skip it if you wanted anyways.
And then, of course, you don't get a straight up damage boost Master skill.
Basically Scavenger, unlike most mastery skills, makes you vaguely bad at dealing...damage, in general, from the one run I've done with it(Ao100 Normal, cleared that.). In exchange, you get more mods, but in general it's one or two rare mods a run tops. At least, based on Ao100, which is more likely to give rare mods than a normal run, it seems like.
And a lot of the best assemblies take rare mods. Especially ones that create playstyle defining weaponry(Nano types...mostly Nano types really, though I think the BFG variants can certainly define a few floors very explosively.).
I can't say that I feel it's totally useless (that nod goes to Survivalist, which seems like it would only save you more than 50 HP a game if you were such a tank that you don't actually need it to clear anyways) but I wouldn't want to take it outside of Ao100(where, at least, the fact that it doesn't block any base traits means that your 15+ levels are better.), or Ao666 I suppose. And it mostly felt like I was using it for laughs there, wouldn't take it on a higher mode than HNTR honestly.
Honestly, seems easiest just to rename it(Techhead or something) and give it the added effect of allowing all (all non-artifact?) items one mod. That way you get more common mods, and always will have something to do with them, no matter what your luck is, and it defines the skill as a generalist more.
I really do like the idea of Firestorm adding fire resistance to armor and Sniper narrowing a shotgun's spread(or maybe lowering its falloff damage penalty%, so that you don't get Doubles going 15 squares suddenly.), incidentally.