I’ve been doing it for probably 8 years now without any major issues related to being a VM. In fact, that made recovery extremely easy the two times my PFsense VM shot itself in the head. Just load the backup of the VM taken the day before and off to the races. After switching to OPNsense a couple years ago I haven’t had a single issue.

These days I run two identically spec’d hypervisors that constantly sync all my VMs to each other over 10GB NICs, so even a hardware failure won’t take out my routing. That is something to consider if you don’t have redundant hypervisors. Not really any different than if your physical router died, just something to plan for.