Not a big deal here but you got numbers wrong (nitue seams to have old weapons' stats).
Avenger burst on range to single target is 14 bullets, p90 5.
avenger bursring on dist from 8 to 21 bullets. (depending on nitue planner.)
Don't even know what's that suppose to mean.
You can't just pick one situation and base your opinion on it. Especially when you pick something that is suppose to be a support for burst damage - partial crits, which should make gap between critical and normal bursts smaller. Also you can't talk about stable when it comes to crits. Another thing worth mentioning here is hit roll. To crit those bullets you got to hit them first and there is a lot more bullets for miniguns ;p You also shot for less AP and got higher damage per bullet so 1 critical bullet for sg makes bigger difference than 1 crit bullet for avenger.
But I won't force or try to make somebody to play on this or that kind of characters, I would not agree thou that crits on burst weapons other than avengers are not working well because I have been playing many of those and I liked what I saw.
I can only provide technical details if I know them, maybe write my opinion but you are free to make your own