This is pretty spot on. I tried something similar a while back and found that the typing latency was on the order of ~120 ms which made it feel mushy and led to a lot of errors. The need to rethink graphics to handle refreshes should not be underestimated. A lot of UI patterns (almost all animations and transitions) rely on a period refresh rate. In order to make a compelling experience you need to rework a good bit of the UI.