well actually u will have ur point since u use it already, but imho as i said there are hard facts about this which dont match with ur telling.
and since ive played everything in max and 5760*1080 on my single gpu so far id doubt that what u say is that true.
And there are already so much posts about probs with xfire only in this forum that that point of urs is to be doubted as well to be honest.
nevertheless, i dont think the initiator of this post does want to buy three double slot high end cards for Xfire, and a new mainboard and due to that also new cpu and memory and so on...
Here's a hard fact for ya only people that have problems complain and write stuff about their problems this is a fact google it. Not sure what you'd consider a problem but doubt what your are saying is a fact.. i'll bench against your PC at max settings my tri vs your single and will see which system truly runs at max settings!