Another benefit is that all items in Inferno at MP 1 or greater now have the ability to roll level 63 affixes regardless of base iLvl.
Have any proof of this?
If this is true then yes mp is better, but I doubt that is true. I am running MP0 as a 100k WW build making 700iph. With MP1 I was at 440iph. Definitely not worth it unless the above statement is true.