LOVE my EoTech.
As already posted, try it out before you buy it, but as long as your eyes are good, the sight will be good for you.
And of course, focus on your target, not the reticle. The idea is that you look at your threat/target, and while maintaining that focus, bring the sight up in line. With practise it's as fast as bringing your gun up. I do a lot of shooting with my AR with Eotech on top, and it is fast. I originally co-witnessed it with a carry-handle iron sight, but I've since switched to the ARMS #40 flip up sight. I keep the sight folded down, it's just there as a back up, but I've never had my Eotech go down anyways. It's a zero-paralax sight, which means that if you can see the reticle, that centre is where the bullet's going.
Some people don't trust it, but with an 11.5" barrel, topped with the Eotoech & the back up sight folded down, I've shot it at 600m. The target was a steel gong the size of a human torso, and after 2 shots to find a point of aim, I hit it every shot for 8 consecutive shots. Some of my other guns can't hit a target that size at 600m 10 times in a row with a 9X Leupold on them, so I don't think that's bad. The sight will shut itself off (I believe after 4 hours) to conserve battery, but for competition use, that's moot anyways.
I use the 512 model; full length, AA batteries. I see no reason to go with a 513, since I don't need the room on the rail, and it really doesn't cut down on weight. And unless you plan on doing a lot of shooting using night vision behind your sight, there's NO reason to buy the 552/553. You'd be better off with a laser anyways in that case.
Cheers.
Tim H