I have to say that I always get the dealer to work on my car. My view is that I won't buy a car if I can't afford to have it serviced within the dealer network. I am reassured by the thought that approved parts will be used and that the engineers dealing with my car have received the proper training and use the right tools for the job. I think it is worth building a good relationship with the dealer, and if and when things go wrong and you have entrusted your car to them over the years, they are more likely to help out. I appreciate that loyalty tends to be a thing of the past, but I also think that if you invest a little time and effort in building a good relationship with the dealer / service staff, it will serve you well in the future. I know most of the staff at my local dealership by name and always have a chat with them. I know them, they know me, and a little politeness and respect go a long way. I am appalled when, while waiting to be dealt with, I hear the condescending tone of some other customers and how they treat dealership staff. Driving an expensive car does not give you the right to treat others with contempt. At the end of the day, when you end up in a garage, you need them more than they need you!
Treat others the way you expect to be treated and they are likely to do the same.
Feel free to disagree!