Just tested it myself, and I was wrong It works with any amount of players... for now...
[SPOiLER]Successful trades/sales : 5
+1 for Bossmode : MM was used, trade was done smoothly.
+1 for axemodemaple : MM used, chill guy, easy to get along with.
+1 for wazzupboy : MM used, sold account easily, REALLY chill guy, fun to talk to.
+1 for Poxer : Sold account w/ MM
+1 for marchcrossfire : He went first, awesome guy
[SPOILER]MauledMPGH@hotmail.com - FAKE!! Don't trust him.
Vladikav69 - I still slap myself for ever accepting to go first