So if it hasn't been said enough, absolutely get the Mod1 the very second you can. It's 200 fragments and some cores for a fair boost in performance. Extra stats, a bit more FP buff on her tiles, a little extra HP, and an improvement to the slowdown effect on the smoke.

The real problem is her 2nd skill is janky and not extremely practical. It's a little bit of a bonus, but not likely to make or break a fight. So yeah, the Mod2 isn't great. The mod 3 however, gives her a unique equipment that goes in the suppressor slot and is basically a suppressor with better stats (+5 EVA over normal) which helps her tanking ability somewhat. Whether this is worth it up to you, but definitely get the Mod1 at least.

The rest of this is basically the same song and dance where she has top class offensive buffs that continue to remain unmatched among SMGs, so you WILL likely continue to use her.

Modded version of M1911

A really expensive trash cleaner.

Basically when she pops smoke, she then goes Alvin York and blasts away 7 times for extra damage, hitting the farthest enemy and working her way closer to the front with every shot. If there are no closer enemies, she just keeps shooting that one until someone else has gotten closer (either because its dead and thus a new thing is closer, or something ran ahead of it).

Note that while the skill has an ICD of 1 second, she doesn't actually start blasting away until 3 seconds in due to the throw animation.