Yes, it's the same as using a custom tag and I believe both are (by default) saved to the MB database.
I personally haven't found myself there yet, but I think other users do run out of custom and virtual tags in the long run.
So generally, I think it's advisable that one avoids using up either of those tags whenever there's another method available.
Incase you may also want an automated solution to this kind of sorting going forward, you can sort by a virtual tag which can use a formula like:
$If($Or(<Album Artist>="Various Artists",<Genre>="Soundtrack"),<Album Artist>,<Album Artist>)
What it basically does is add a (zero-width) space to Album Artist whenever the genre is soundtrack or the album artist is various artists.
You can add to those conditions as you go on. Virtual tags are for display only - they're also never saved to your music files...only to the MB database.
I already spend hours on end on social media. Might as well spare a few of those to a greater purpose here.