Hi Paul and welcome!
Judging from previous threads on here, I think it's fair to say that the great majority of Abarthisti pamper their cars but not, as you rightly say, by paying franchised Abarth dealer prices, at least not once their car is out of warranty. The 6k mile oil change is key, as with any turbo'd car. Many of us find a trusted local mechanic who is as daft about performance cars as we are and get them to do the jobs we can't. My local guy is an ex BTCC mechanic and is an absolute whizz - plus his hourly rate is only half that of the dealer; and he doesn't mind me sourcing parts on line either (oem, of course).
So a well stocked file of bills and receipts probably counts for at least as much as a stamped-up service book. As all the pundits say, buy on condition rather than miles. If it looks well loved, it's likely to be so.
Enjoy whichever model you choose.