I have this level1techs KVM which can drive my 5120x1440 @ 120hz monitor (without DSC) AND my 3840x2160 @ 240hz monitor (also without DSC). It's $450, but Wendell and level1techs are great and it's well worth the price.
I'm running Fedora on one host and Ubuntu on the other. With Windows, you can use DSC to drive huge resolutions at 240hz.