Mamba:
I can say, I'm jealous of you..I have the Deathadder, which is what they based the Mamba off of, and I LOVE IT. It does have the double clicking bug, but hey, it's so comfortable.
Arc Mouse:
It looks somewhat uncomfortable.
Personally I'd get something like this:
http://www.newegg.com/Product/Produc...82E16826104203
Yes it's a gaming mouse, but gaming mouse offers comfort.