He made several statements that are not true;
1) If my hot water tank had black PVC exhaust piping it was illegal and dangerous.
If your gas fired hot water tank has black PVC piping or a metal direct vent stack it is not illegal or dangerous. The code has been changed and black PVC is no longer used, however you don't need to change it until you change your tank.
2) The company we rent our hot water tank has hired his company to come in and do an inspection.
The company my hot water tank is with has not hired a competitor to service or inspect their hot water tanks.
3) The new tanks are 95% efficient compared to a tank that is 10 years old.
The tank supplied by the company he works for is identical to the one in my basement. A little research says that a tank will last up to 15 years and that the decrease in efficiency is less than 6.3%.
A great website with a lot of information about hot water tanks is http://www.burnedatthedoor.com/facts-myths.php
Another great website is https://www.ontario.ca/consumers/door-door-sales-and-home-service-contracts
Protect yourself and your family. Before you sign for a new water heater do your research.