I decided to keep my X another year. Battery was at 85%, so I called AppleCare last week and asked if I could use one of my AppleCare+ incidents to get a replacement before my coverage runs out next week. They agreed, and I got a free replacement.
The store had to check into it as they said you normally can’t use AppleCare for a replacement if it’s still over 80%. They found the notes from the call showing that it had been authorised and promptly replaced it for me.
Worth a call to AppleCare if you still have coverage and want to keep your phone another year.