Unless you put a manual switch on backup or use a Vision Pro with backup shut off above a certain temp, you may not get around having backup come on.

Houses have a balance point where the heat loss is the same as the heat pump's output. Near or below that point, you WILL NOT warm the house backup without backup. It can't be done no matter how smart the stat.

If you are in a mild climate, I'd get the Vision Pro and lock the backup out at as cold a setting as you can.

As for high end York, they have the Stealth which is a TS R22 unit and the Affinity 15 which is a R410a with unloading scroll.

Has the XL16i been trouble? The models with the 2 clunker recips I hear tend to chew up the little guy in heat pumps.