We had a discussion here regarding that monitor before, and as pointed out it is NOT 240Hz. It is a GOOD 120Hz panel, BUT... You need to decide if it is worth the $200+ over current 144Hz panels.
It is VA, which offers better color reproduction to the TN panels on the market and it boasts a damn good 120Hz when looking at motion tests(funny enough 240Hz is sluggish in the motion tests in comparison). A very solid panel if you went that route. I just feel that if I'm going to drop around $550 on a monitor right now, I may as well save a little more and grab the Acer XB270HU bprz as it is 144Hz, IPS, has G-Sync, and can be had for $720~.
http://us.acer.com/ac/en/US/content/model/UM.HB0AA.001
Use promo code for 10% off:
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Now considering the vid card you run, unless you upgraded, it wouldn't seem feasible to grab a 2560x1440 panel to game on. If I were you and had that card, I would save the $200 from buying that Eizo and just pick up a BenQ XL2411Z or ASUS VG248QE.
As a heads up from someone who did the competitive scene thing back in the Source glory days, my advice to you is to learn playing at 1920x1080 and find mouse settings that work properly for you at that resolution.