Just installed 6 of the AOC 34" widescreens (not curved) and am very happy. Used a Vision Tek graphics card (about $250) but the AMD Firepro 4100 is probably a better option but you need two of them. Running at 3440x1800.
3 large charts per screen, 3 markets followed, Cable, Euro and EUR-AUD. Yes, that's only 3 but I like to look at the reverse crosses as well so USD-GBP etc. The reverse charts appear on the screens above so 3 screens on the bottom and 3 above. Also bought a sit/stand electric desk so I can stand up for half the day especially inthe mornings.
The free (or paid) monitor management software Display Fusion is great for setting the monitors up and getting the mouse to move easily between them.
I used to have 2 screens but found I was losing concentration having to flick between the different markets. Now I have all my charts right in front of me all the time.