What's wrong with the MAXX is latency. Each frame is still rendered by one single graphics chip. The time since you move the mouse until you see the movement on the screen is the same as if you had half the FPS.
E.g., if you play at high resolution and get, say, 40 fps... your control of the game is basically the same as if you had only 20 fps.
Which basically makes the games look smoother, but fails to address the real reason people often quote for needing better speed. That reason is: ease of control. If your fps drops to, say, 10 fps, it becomes a pain in the behind to control the game. Anyone can tell you that if you drop to 10fps in a missle duel, you're dead meat. What happens is: by the time you see the crosshair on the target, you've already overshot it by a few degrees. Not only that, but the same delay happens to the target's own positioning. By the time you finally took correct aim at its position, you're actually aiming at where it was 100ms before.
Only on a MAXX, the same happens at twice the fps. When you think you're getting a decent 30 fps, you're getting as much delay as for 15 fps. Worse yet, looking at the fps counter you don't even have a clue that it's bad, and you need to decrease your resolution. You're dead meat, even though your fps counter says you shouldn't be. And even worse yet, no matter how much you decrease the resolution, you can't drop under your FPU's processing limit. If your FPU can compute triangles for at most 40 fps, that's it. No matter how much you lower the res, you can't get more than that. Only on a MAXX, your control accuracy will be half that: 20 fps. Your minimum possible control delay is as if your CPU was half speed.
Mind you, I'm not saying you actually need 60fps for good control accuracy. Most of the time 20..30 will do just as well. Plus, if nothing else, the delay most often depends just as much on the mouse drivers and other factors. (E.g., if your mouse only reports 20 times a second, having 100 fps won't help THAT much.)
But I'm saying that the MAXX doesn't really make this problem any easier. It's a scam to make it look better in benchmarks, without actually being better for game control purposes.
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Moraelin -- the proud member of the Idiots' Guild