Now on osx I run dev db and other server as needed. Nice to roll back to snapshot
Fits in tool box for non automated, as hoc servers. Dont have to configure anything, or write script. Just acts like buying new hardware and slipping in CD.
Even with a 256GB drive and a number of tweaks like hosting the Windows pagefile and temp from a passthrough disk, disabling Windows automatic updates, and using an immutable disk containing the OS install/multi-attach for copy-on-write behavior, VBox still used a ton of space to track the differences from my baseline snapshots. Even starting the VM quickly consumed 10-20GB in the new disk image. Was hard to conclude anything other than it wasn't a viable "dual workstation" setup and I capitulated and moved to Windows 10.
Sucks, because it was really quite nice to have a unix under the hood, though WSL makes this a bit more tolerable in Win 10 AU.
All in all though, if you ultimately moved to a native Windows 10, therefore allocated X space of native disk, the space requirement is not different from having only a virtualized one with X space of virtualized disk (heck, you could even pass a partition).
Having said that, if 10-20 GB of space are taken so quickly on boot, it may be worth investigating (you could even vim the diff disk), but I find your claim somewhat misleading, as you're likely experiencing this on the first absolute boot after taking then snapshot, but not on the subsequent ones; therefore, if your system steadily takes 20+20 GB of space, that's a perfectly reasonable requirement.