Hi,
Mach4 works perfectly well with a touch screen. A touch screen is a Windows feature, not really Mach at all.
The real issue is that the Mach4 screen has a lot going on and touch screens have course resolution, the consequence is that it's too easy to hit
the 'button next door', a PITA.
I used a laptop with a touch screen for a while; soon learned to avoid using it, aside from putting greasy smears all over the screen.
If you are prepared to make your own screen set but with very much fewer buttons and elements then a touch screen would be fine.
Craig