Since this old thread got revived, I thought I'd throw in my two cents: when the MP first came out I wanted one badly, or so I thought. Then I realised that for the money I could buy 4, 5, maybe 6 user M4-Ps. So the super reliability argument got shot down. I got two M4-Ps instead.
There is of course the built-in meter in the MP, which I wouldn't use anyway because a hand-held incident meter is better...