Can't help you with the main question unfortunately. However, I'd just say that if the car has a Mazda dealer history up until now, it's worth considering keeping on with that. If you have any engine issues post-warranty, having a Mazda servicer history seems vital to getting any goodwill out of Mazda towards repairs. There were some 2015's that were fitted with LED drl's that have been known to have issues, they are VERY expensive to replace. If you have a search on here you'll find posts about these and some of the possible engine issues (and how to avoid them).
Alan
