I have the LG 29" that I picked up for $339 on sale from Newegg last week, and let me tell you gaming is so much more immersive. I have no experience with eyefinity, but I imagine if you can get past the bezel annoyance, it might give you more peripheral vision. IMO I think ultra widescreen would be more practical.
I tried a few games and so far the difference between 16:9 and 21: 9 seems quite large. Toggling back and forth between 1290X1080 and 2560X1080, the choice is clear that 21:9 is the way to go.
If you choose the forego eyefinity for an ultra wide, I don't think you will be disappointed.
Edited by aweir - 4/10/14 at 11:00pm