I agree though, 60hz is a pain in the eyes. You look in one corner and you can see flicker in the other corner. I've heard some people cant see it some people can. Play it safe and set it to 85. 60 gives alot of people headaches and is distracting.
60Hz is more than adequate for a TFT display without causing eye strain, plus it gives you an extra 40% processor time to play with in your main loop.
As it's such a subjective thing, the best thing to do is simply to let the user choose for themselves. c.f. Halo PC, GTA and many others.