I like the idea, but there would be limitations. You cannot use a momentary tap function when there is a hold function also assigned to that switch. This is currently the case with momentary Control Switches and would have to be the case with any other momentary function. Hold functions on switches themselves also have two activation methods: on hold timeout and on release. The on release activation of hold functions would also not work with any momentary functions. Another is that Fractal allows for the use of latching external switches. Those too will not work with any momentary functions. None of these are necessarily deal breakers, but still things to keep in mind.
So after poking around you CAN do momentary switch by assigning an action to a CS, and it works pretty well. I do wish it was expanded to work with Scenes though. That would be epic.
That's not going to be momentary as far as I'm aware...You can use CS MIDI and a loopback cable to change scenes.