I always played on some MP setting during my run so far, depending on gear. Whenever I got upgrades I'd go for MP7-8 then lower it gradually until my next upgrade.
When I hit 60 and got the gear I have now I could finish Hell on MP7-9 and I was even running with PtV passive and AC:AR for the large AoE. I would run oom ocasionally, but everything was just melting in front of me and it was fast
When I hit Inferno, I lowered to MP2 and... couldn't even kill the fist elite pack w/o dying twice... Bummer!
I'm thinking ok, I'll try a build that requires a bit more work (positioning, keeping another buff up) but should be more effective. So i gave up PtV passive for Jungle fortitude, gave up dogs for Hex and switched to bears from AC. And went down to MP1. Now it was about 50/50 (on dying or not) with the elites, depending on their abilities, location and other mobs in the area. But still quite a struggle and nowhere near efficient, the problem being I get 2-3 shot by elites.
At this point I went down to MP0 and - surprise, surprise! - it's a walk in the park.
So... sorry for the long post, but here are my 2 main points:
1. WTF at the difference between MP0 and MP1?! They should do just 9% more damage, but it feels more like rabid dogs vs. cute puppies.
2. Could you help me with some advice (next upgrades, different build for my current gear) for being able to do MP1-2 w/o dying as much?