I was also wondering about this. I have the slag turrets but I also put enough points into the middle tree so I could get the longbow turret and the double health for it. Unfortunately that also prevents me from ever getting the double turret unless they do another level cap (which I don't think they'll do, IMO). Should I forget some of the right tree and go straight for the nuke instead?
There's a dude in the bushes--HE'S GOT A GUN, what's he doin? I don't know I don't know, RED TEAM GO RED TEAM GO!