Is the ammo distribution different on hard? I think the necros are probably worse, though this is my first playthrough. It takes 4 shots, close range and good aim, 2 leg, 2 arm (or some variant) to kill a standard ripper with a plasma cutter, and the others are just insane, usually 7-10 unless you can dismember them.
I've only focused on 2 guns with the nodes, since so many options tend to leave me standing at the work bench for 30 minutes trying to decide what to upgrade. This has helped, though. I think you're right, I need to ditch 2 of the guns. I was trying to have many options in case of a boss or necro that was only killed by a specific type of damage/weapon.
I've encountered that in other games and been screwed, lol.