I got quotes for new systems in 17 yr old house. The Carrier rep with Puron systems was the lowest bidder by severral thousand $$$. This eliminated the philosophical dispute. However, the quote included 2 new programmable thermostats and a new condensate pump. When asked if these were required (since my current ones are fairly new), I got the following response.
We prefer to use the new thermostats with the new systems because older thermostat circuit boards do not communicate with the new system circuit boards. We could have a potential problem in the future with older thermostats. This added approximately $55.00 per thermostat to the quote.
the new cooling coils produce about 2x the water as older cooling coils and we prefer to use the new condensate pump for this reason.
I don't want to be cheap but neither do I want to be taken for an idiot. Is the guy correct or blowing smoke?