All the software I use works fine (I'm using Virtualbox on Mint with an i5) and have had about 15 VMs running simultaneously (could do with a bit more RAM!) whilst doing stuff (using GNS3 and such like).
I run W10 in Virtualbox under Mint. The W10 licence is the one the machine inherited when it upgraded from its original W7 and it hasn't complained (so far) about its validity. The W10 install is there purely to run Photoshop: in every other respect dropping Windows in favour of Linux was the best thing I've done in ages.
I use virtualisation a fair bit using VirtualBox and it works well for me. I have a Win 10 virtual machine on top of a Win 10 host to cope with a Microsoft oddity; a Win XP machine to run one very ancient piece of software and a couple of Linux virtual machines. All works well for me but it will depend on the software you are trying to run.
This is all good news, and maybe I don't need to bother with the Robolinux hand-holding. I would still like to know what this compatibility business is all about though, presumably it also applies to other flavours of Linux.
A few years ago I setup a virtual machine to run WinXP under CentOS. This was using the standard libvirt package which comes with CentOS.
I couldn't be bothered with reinstalling WinXP and the applications from scratch so I just cloned its disk (which was pretty full) into an empty lvm volume and then imported it into libvirt.
My intention is to migrate to native Linux applications, but I constantly need to "get stuff done" so I need a smooth transition with a known fallback* (ie what I did before the switch). The idea of simply copying my existing installation is appealing (although I imagine I would need to uninstall RollbackRX). That's one of the features specifically tailored into the Robolinux package (at a cost).
For anything I definitely need Windows for, I could set up a fresh Win7 VM optimised for that specific use, post migration. I don't see myself moving away from CorelDRAW for example, and a potential future project will require installation of a variety of versions of MS Office.
There is also the question of hardware support. I need to check whether my printers etc are supported in Linux, and if not I guess they won't work in a Windows VM hosted in Linux either, and dual-booting is required.
However, this is all getting a little ahead of itself. The primary driver is to get a Win VM (any Win VM) up and running on existing hardware (not new hardware yet) before the MS deadline. Then, presumably, the VM can be copied to a new host with no issues whatsoever.
* The ultimate fallback is to turn on the old PC! That could work if all my files are shared on a NAS rather than stored on the PC.