I just started with Xenforo last week and have had some very positive experiences along the way.
First I took a license off someones hands which saved me 10-20 bucks which was fine, but more importantly the person needed the cash quick and plans to get a new license when his personal life allows.
Second I traded a resource for the service of setting up my VPS with all the fun Linux stuff that is better left to the experts.
The two interactions were good-spirited. Good trades without the need for escrow really highlights the integrity of the Xenforo Community.
Can we swear here? Tell ya what, "I wish Diarrhea on Enjin"