I have often wanted to ask some hardcore Necromunda peoples this question, this seems like a good chance.
What are your opinions on a gang made from lego? Fixed onto the correct size bases of course. Any opinions on scale? they seem about the same to me, though I am not a stickler and have not compared properly.
I mean, the first question is why not play a game designed for lego warfare, if using lego minis?
https://brikwars.com/
Anyway, regarding legos in necromunda, it really depends on your players. You could just all use the legos and then it wouldn't be an issue at all.
Also, I think motives matter. Like are you doing it because you don't want to bother painting your gang and/or because you don't want to pay retail buying GW gangs?
I do find it offensive when my opponent keeps talking about how cheap their models are, and how stupid it is putting time into the hobby.... I'm sure they don't intend to offend, but they are indirectly insulting my purchases and insulting my time spent painting and/or converting. And we could still have fun, but just saying that it's offensive to me and I'd really prefer they were more respectful.
Don't get me wrong, you can be bad at painting, or just never get around to painting, or proxy things you don't yet have models for, and that doesn't bug me - it's less about your guys, and more about your attitude towards the hobby end of a hobby game, since I'm rather devoted/obsessed with the hobby end of this game.