When you are looking at a system replacement, many things should be carefully considered.
I’d say at least 50 percent of the existing systems we see are inherently inefficient, usually due to undersized supply or return ducts (usually the return), leaky ductwork, incorrectly sized refrigerant lines and other factors. These should be carefully evaluated by a qualified design tech and corrected if necessary at the time of replacement. This is the most cost effective time to address these issues. If you don’t, all the extra efficiency you pay for be will be eaten up in unnecessary energy costs, not to mention the service related problems that go along with incorrect design parameters. Unfortunately this is what we see on a good majority of the existing systems we’re called in on.
When you’re looking at an investment as substantial as this, careful consideration is wise.
My advice, whatever it’s worth to you, is this:
Rather than cold calling with price as your focus, find someone you feel is honest and qualified. Let them evaluate your needs from an engineering standpoint and discuss your wants and desires. Based on that, make an informed qualified decision. If you base your decision on that you will end up with what you want and need and not fall victim to a costly mistake.
This is a big investment anyway you look at it and you’re going to have to live with the result for a long time. It would be real easy to allow a contractor to put his wants over your needs and take away the value you deserve.