we had the Insinkerator in place for a few years and a short time after it was installed we suspected a slight leak or weep but were not able to see it or actually determine it was from the instant hot water unit.
when I was installing the new dishwasher I found that it was in fact leaking from the discharge port due to a loose connection that required disassembly to tighten. When disassembled it was simple to tighten the leaking connection, however, i was unable to find a way to seal the chamber flange or replace the small plastic hose from the unit discharge to the chamber on top of the unit. Parts were not available from Insinkerator, so the unit was a throw away. I really hate to throw away anything that is repairable for lack of parts. That seems to be the current corporate mindset.