Hi IainLyon, welcome to the forum!
It's impossible to say anything about performance or critical issues. Your environment is not our environment.
If you plan to upgrade VC, I suggest adding a test server and install the latest VC version on it. You could restore a backup of your older VC version, but be aware of two VC servers handling the same triggers. You also can start testing a fresh VC installation on the test server.
... or ...
You might be able to make a snapshot of the server, update the current VC version and test it for a while. If ok, stick to it, if not, restore the snapshot.
I'm using VC for 13 years now and am not disappointed. Currently on 8.3.4, but my next update is scheduled for the upcomming month.
Uses Visualcron since 2006.