Just had my third service at the Abarth dealer who supplied the car: it cost the same as the second service, so not sure how you distinguish between 'big' and 'small' services. Interestingly, I had a long chat with the senior technician as we went out for a drive in it to see what he thought about a possible diff noise (warranty date coming up, wanted to cover all the bases). He was telling me that they've had real issues with resetting ECUs, because of the Fiat/Mazda electronic interface and logging on with the system in Turin. However on the plus side, they've had a fair number of people wanting to replace their two-year-old Abarths with a new one, who have not been happy to learn there are no new ones.
I think, at the moment, I'll be sticking with Abarth dealer services for a few more years. Sure, my local guys can service this car, but they won't have access to the manufacturer system, and at the moment it's a long term keeper (my wife loves it), so I'm happy to pay an extra hundred quid or so for someone who knows the wrinkles. Don't judge a dealership by the front of house staff, talk to the senior techs. Knowing the trade helps, but these are the important guys.