If you don't plan on modding id say the extended plan on this car would be a good idea. Granted, the reason I say that is having been a member and heard issues on this forum for the past few years
I realize there are a lot more of these cars on the road than a forum represents so information about how this car is doing overall is limitted to public opinion and the opinion of ppl who like to mod
I would say that because this car is turbo parts will generally be under more stress and have a higher failure rate than NA cars....but this is a very general statement. Also, there have been many concerns about direct injection lately, mostly stemming from vw, that has ppl worried about the longevity of this car
I would say to get a good idea go check out a consumer report, but on the ms6 or older cx7, they have the same engine basically, and see how they are fairing with higher mileage and repair reports (because the 2.3 turbo has been in those cars longer than the ms3)
Or the dealer was just trying to upsell you, and says that about every car