Yes, MP0 means that it's disabled.Quote from SolTheDruid
Just to clarify: MP0 means disabled MP system (which is the default, I believe)?
Also, as I recall, Blizzard were saying that the current Inferno difficulty level will be at MP2 due to monster damage nerfs. Is that so on PTR?
But depending on your progress, MP2 might be harder than what 1.0.4 is, since it will bump all monsters to lvl63, so if you're playing in a1 or a2 and barely surviving, you might be better of running with MP disabled.