No, just play it safe dude.
Legit and simple forum software, but i disagree on this upgrade, due to the fact that i DONT WANNA LOSE MY POST COUNTS!W!WS!S!!!!!
vBulletin vs xenforo.
I've no idea. I don't mind staying on vB actually. Also, there aren't many skins of Xenforo or none..
Xenforo itself looks kind of pretty.
Im 99% sure vbseo will support XenForo simply because so many people are converting to XenForo.