x-Pro1, D800E and 5DIII best for Weddings?

A DSLR is going to be better for weddings hands down, as you need fast AF and overall reliability. It's more like sports shooting than reportage, given the amount going on in a short space of time.

A rangefinder clone will be great for street shooting and documentary reportage where small size, low weight and unintrusiveness are all more important than speed. But that's a far slower kind of shooting, to my mind.

And previous comments notwithstanding, wedding guests are generally okay with the fact there's going to be a pro photog in the room waving a ton of equipment around - it tends to go with the turf.

Edit to add - of course, there are always the exceptions that prove the rule. I'd break out the D700 if I were shooting a wedding though.