So I'm on a vacation, and I thought it'd be a perfect time to try out using FL Studio on my Surface tablet, using just a pen. And guys, turns out it's pretty effortless! You can do pretty much everything with it that you can do with a mouse, except proper scrolling, which I'm sure people found how to emulate with a pen somehow - and everything has a scrollbar anyway.
The most important thing a pen allows you to do is hovering over UI elements, which you can't do just with a touchscreen. More precision!
Tiny piece that I made with this setup attached. Will probably try continuing it with my proper PC where I have all my plugins, except just Phonec and Vectomelt.