I can't even imagine using a single 7970 for eyefinity when even 7970 cf barely cuts it for heavy games
I might not be the best yardstick for comparison. It's a sim rig and unfortunately a number of sims don't seem to support crossfire. Right now it's either running DCS A10 or iRacing, neither of which support crossfire. If they supported crossfire I'd have a second 7970 in there right away.
Actually they both do pretty well with a single card, I get 30-40FPS from DCS A10 and alot more from iRacing, with generally high graphics settings.
I haven't noticed any tearing in those games, I can't say for sure it isn't there but it certainly hasn't manifested itself to the point I have noticed. I will make sure to focus on the outside monitors as the focus is usually more on the centre monitor for obvious reasons.
I did take Metro 2033 for a spin a while back and had bad tearing.
I used to run a 5970 and that had horrible tearing in various different FPS games (Metro 2033, Stalker) running Eyefinity but again I didn't really have many issues in any sims I ran, there were just horsepower issues with the high resolution so I had to back down on the settings.
The model is the Sapphire 7970.