Oddly enough, I've been taking the tier-6 bounties lately as the ones with only two opponents are easy enough, and I've found my 'A-Team' of Rebecca, Ayden, Space Marine, Felix and myself can take out the worst of them, the ones with where the bounty is as good as the Black Gunner and there's an Elite Soldier and two others as well. I've not gone down since my first couple tries, I think he changed some things and perhaps I just ran into crits at the first and didn't realize it.
For one thing they're not firing first anymore, so that combination firing four auto-hit plasma guns and Ayden's first volley is enough to take out the bounty with some left over for the Black Gunner. That means I only have to take one Plasma hit and with all the goodies I have that can be managed.
One thing though, it's rough on your armor, my Quartermaster Averill can't keep up. I've had to stop by Westside armor at least twice to get repairs when getting back-to-back tier-6 toughies.