You complain about AMR's killing Power Armored chars with just a few shots in NV, but the thing is, that's what AMRs were initially designed to do. They were used to scrap Tanks and Howitzers in WWI.
Started replaying Fallout 3 recently, without TTW this time and with FWE. Sentry Bots have 500 Health and 76% DR with FWE. They're absolutely ridiculous to kill. It takes a full drum from Eugene to kill them (at 100 Big Guns skill), that's like 250 shots, with all of them hitting the Torso. With FWE and T-51b Power Armor+Perks, i have 95% DR. Big hitters such as Missile Launchers, Sniper Rifles, Plasma Rifles and Grenades don't do [censored] to either me or the Sentry Bot. I can even take a Fat Man's Mini Nuke to the face and survive. Full auto weps though will start to tear into me. When it comes to pure DR, DPS is absolute King. No if, and, or buts about it.