You brought exactly the point that keeps bothering me... I'd love to try a first person perspective, yet there are two things that still keep me from going "alright, let's do this"...

a) I'd really like to make a third person game. I know it sounds silly but I'd just like to try on one. And, well, the idea of doing a third person mp shooter came to my mind BEFORE I had the idea of spicing it up with parkour/freerunning...

b) Some things will be incredibly harder in first person, from the view of a developer. For example, if I'd do a first person view, it'd be a "real" first person view - no floating hands with weapon and another model for the rest of the body or something like that, just one model. And that would make things like aiming down sights more difficult to realize.
Also, the generel detail, graphically speaking, would have to be higher.

Well, you see, I'm confused.