Yes, of course one shouldn't make similar experiments with production VMs; anyway, one should always keep full backups of the VMs!
... My OS X 10.8.5 VM is of the correct type; I temporarily switched its language to English, so here are also the correct terms for the virtual HD in System Information:
Removable Media: Yes
Detachable Drive: No
I also noticed that itidentifies the drive as being an SSD: which is correct, too, because I have all the VMs on an Optibay SSD in the former SuperDrive bay on my MacBook Pro (and the main boot drive is also an SSD, of the same type); BTW, should I enable TRIM also inside the VM, or is it enough to have it enabled in the host?
IIRC, it should probably be enough to have TRIM enabled only on the Mac side (also as the VMs are simply files for the host system) - but just to be sure...