Feeders= 1,2,3 that many hit and run attacks 4,5,6 one auto damage (which has the standard chance to crit) and one hit and run. All hit and runs are 1 die.
What boarding modifiers are you using there?
Nids got choice of 2d6 and ignore blast markers previously. The +2 simplifies that, although I still like +3 to place them above the rest.