If we could expect every single bullet hit ( no criticals ) on a guy with BA+2xToughness and while having 2x BRD, avenger would do better average damage per burst, while LSW possibly making more damage.
Psycho would change damage of both weapons by the same amount I guess.
Ofcourse this is with AP ammunition, JHP would do very little damage.
Solar, i've shot a friend of mine at 2 hexes range with an avenger minigun with AP rounds while he was in a bluesuit just for a test.
I've heard, that with lower skill avenger tends to miss a lot of bullets, decreasing damage dramaticly. I don't play burst specs so I haven't bothered searching how it works, but it'd be probably the best thing to check out when comparing weapons that shoot really a lot of bullets.