Edit: I’m glad so many of you have had no issues with multiple monitors. My set up is a little unusual (3rd display is an infrequently used large tv hooked through the receiver) and is definitely solveable but will take some effort (and honestly, I’d rather spend my spare time outside or with friends, so who knows when I’ll fix it.)
It works fine for everything else. Besides, X11 doesn’t even support two monitors with different refresh rates.
And you fell for the good old “humans can only see in 35Hz”.