We have used Comfort Air for Ober 20 years. That should speak for itself.
There's no high pressure to change or upgrade we have experienced but they provide you a heads up as to the expected life expectancy of your system. I thought of our system as still new, but it actually was installed around 2001, so now, I have to plan to replace it as more of the system components fall out of the manufacturing specifications. This past time I passed on doing a $270 capacitor change even though it was out of spec because I realized that the system was quite old, contrary to what I thought. There was no pressure to change, but I had the facts to know that I has an old system with outdated refrigerant so soon the cost of the parts may not justify a repair, I should be prepared for a system replacement.