had the second heater in 20 years spring a leak requiring replacement of the heater/reservoir. The new heater/reservoir was the same as the old one except the new one needed an adapter to attach the existing plumbing. the adapter had to be ordered separately. The kitchen sink was torn apart for a week awaiting the adapter. To their credit Insinkerator shipped the part free of charge.
A second issue is that heater/reservoir had to be ordered with an inline water filter. The filter was accompanied by 2 short pieces of nylon tubing but no connecters or instructions on how to install the filter. 
Since these units have a 10 year service life without the filter, hopefully I will be out of this house before it needs to be replaced