All of the rifles go wrong from time to time. The FTP is a fairly new gun at there were some problems with some of the early ones. I was lucky enough to win one last year and it's been fine, though I haven't used it much. Pure accuracy is superb and the stock is fantastic. If Air Arms are prepared to sell you a gun I would hope that they would also provide some support.
I also have a year old Steyr LG110. This has not been touched in any way and it's been faultless. By reputation the Steyr is very easy to work on with good online guides to allow you to service the gun step-by-step. From this angle The Steyr might be the best option.
It's pointless wondering whether any of these guns are 'better' than the other, all will take down any target as long as the gun is correctly set up with suitable slugs.
I know of a 7 year old Steyr which has never been touched and takes down a hell of a lot of tin chickens....