Opinions needed from all you hardcore Coral growers

[GMGQ]

By definition, a Quarantine Tank should be an entirely separate and isolated system. If you share a sump, it's not an isolated quarantine anymore.

Just imagine if there were some flatworms on a new coral, and they get blown into the water column, into the sump, then into the other tanks, etc etc. -- you get the picture.

If you're doing a crazy huge setup like you're talking about, I would definitely do an isolated quarantine tank for safety. You can treat new additions with copper and what have you before introducing them into the main system. Plus if you're gonna have so many tanks anyways, the cost of another skimmer & equipment for the quarantine will be a drop in the bucket :P

Think of it as insurance.