The absolute best place to buy your HTL is from CCM. They have cat 1 and cat 2 with the double pilot operated check valves. Call and ask for Mark. He posts here under the screen name CCI.
I have never heard of any of the concerns your dealer is talking about. Maybe Mark can give you some of his expert insight into any issues there may be (if any at all).
You can also take a look at their FAQ as it will answer many of your questions.
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