I am happy with sharpcap.

My biggest reason to try stellarmate X is the same as my reason to use stellarmate (where I started): the ability to do live stacking and control my rig from a mobile device. The inability to control from my phone (unless I like pain) is the biggest limitations of my current windows setup.

Firecapture works with SM X, so you have a great piece of software for planetary imaging and you have Ekos/Kstars for everything else (deep sky and live stacking). It would probalby be easier to try and learn Firecapture that to have your mini PC set up with two SSDs and two operating systems.

Kstars and ekos does not live stack, as far as I know. The stellarmate app does. I do EAA most of the time, and planetary imaging very occasionally. So the EAA functionality is more critical for me.

When I used stellarmate with the rpi it was quite unstable. Random crashes, the equipment profiles were especially annoying and didn't work. That's why I would like to try stellarmate x without destroying my currently working windows setup.

I would also be interested in switching over to Stellarmate X from kstars/ekos on my Mele if it can be done while preserving the windows installation on the internal drive. I have Ubuntu on an SSD but I use windows when I need to do firmware updates for various bits of hardware - generally those require a windows installation and I am pretty much Mac and Linux.

There is no problem with reinstalling windows. Since a few years, the product key is the processor.
The OS is attached to the kind of cpu the machine was built with.
If you bought a machine with w10 pro installed, and you then buy another which was presintalled with home, you will not be able to reinstall your own version.
But if you buy one with w11 pro, then you can restore your backup on it and it will work (modulo the need to update the drivers).
I did this twice in six years with a HD that I brought from a laptop to another, then to a mini-pc. And it was w10, not linux (for which it works flawlessy with not even the need to go for drivers hunt).

Er... multipass... (sorry could not resist to te temptation): multiboot ?
On the prompt, at install, select Install [the linux distro] beside Windows.
Yes, of course : do make a backup first (clonezilla is good at this).
J.-L.