Just tried out .4. Pop boost 5, 100 max thugs, 50 per tick, melee weapons only... EVERYONE brawling, cops blowing groups of people away, and carcrews mounting the sidewalk and plowing down everyone. Fantastic.
If weapon chances work now, I'll try sprinkling in some guys with shotguns.
This made me think of an option that might make things interesting. I don't know the difficulty of your code, but would it be possible to make the thugs friendly toward each other but enemies to normal peds/cops/player, so they would act as a mob and gang up on police and such? Like:
Thugs Attack Police Only
Thugs Attack Peds and Police
Thugs Attack All Except Thugs
30 thugs bumrushing a squad car would be quite the spectical.