I had to replace my a/c in our last home and here is a few things I did while researching the options.

- I did not go with the XB-13. It's the basic builder's model and went one above that level.

- I got ten estimates. I liked TRANE and that seemed to hold up best in South Florida. I think American Standard owns Trane but not sure if they make Trane/AS in the same factory. In South Florida there are more HVAC contractors than gators so it was best to get a lot of bids.

- Our current home has a 11 year old Trane XR12/Variable speed air handler (iT came with the house, we have been here 4.5 years) and it has worked perfectly except for replacing a contact switch 3 years ago in the air handler. It is very quiet too. My neighbor has a AS system and it's loud as hell.

- The bids were for the same equipment options (XR-13) with variable speed air handler, 2.5 ton.

- The bids estimates were about 2-4 thousand dollars difference from the various HVAC contractors so there is a lot of wiggle room with HVAC contractors. I felt some of the bids were high based on the "throw a number out there and hope it sticks" model of bidding.

- The company I went with was a son/father company that had been in business for 10 years. The son owned the company and was very friendly and knowledgeable. He explored all the different options and explained the plus and minus with each one. We chatted for about 2 hours. The other contractors limited their selling to about 20 minutes and I can understand that due to time is money for them.

- The son/father company I hired did a great job and I was very happy with the Trane. It was very quiet and my electric bill did go down a bit. (Replaced a 20 year old Trane).

- I recently called the person that bought that home and he reported zero problems with the Trane XR-13. It's been 6 years since it was installed so that is pretty good.

- The installation is the key and there are a lot of shoddy HVAC companies (like any profession), so going with a company that has good recommendations is key.

- Also, you might look at your vents/ducts before you do the new install. Look for leaks, gaps etc...if it is flex duct see if any tears etc....

- Are they going to replace the old copper line sets? I would think so but sometimes they just flush them and reuse them. The old gas is R22 and the new gas is R410 .
I spent about 3 weeks reading about HVAC on the various forums etc....to get up to speed on the technology and options before I got my first bid and still there were many things to discuss.

Good luck!

Thanks for the info!