one of the issues with heating systems, is that for most people it's a distress purchase. Most people don't replace their boiler cos it's 20 years old and it's a good idea. They do it cos it's 20 years old and it just broke.
Ten years from a ASHP doesn't feel totally unreasonable if it's 7k, that's 58 quid a month. Stick that in a savings account each month, and after ten years you have the money anyway. Yes, there is the issue with non interoperability of parts from the first generations. Unfortunately that's common with most technologies. (try plugging in a 100 year old electrical appliance). As the tech becomes more pervasive, and more mature, the interoperability will improve.
Sorry to say that some of you are paying the price for being early adopters, but I would hope it's improving.
J