The independent Ferrari mechanic here in Austin (FChatter "Speedmoore") can do anything a Ferrari dealer can plus much more. He is also a race Engineer, so he can and does invent new parts for Ferraris.
I am certainly not the only one, there are many in Socal and for that matter all over the US. Dave Helm in Colorado and I have pretty much matching careers. I've worked in Ferrari franchises since new Ferrari's had carbs. Was shop foreman at largest volume Ferrari dealer in NA. Now I have my own shop. Prob the only guy in Norcal equipped and experienced in 360 gear box overhaul. Extensive experience in engine management and F1 diagnosis. Factory trained thru 575. I was also offered several jobs by FNA over the years including running a Ferrari mechanic training center here in Norcal. Not specific product training, that is all done in NJ. but more of a tech school. I turned all offers down over compensation issues. Only one other guy in this market area can come close to the combination of my experience and training on the late model cars and he is very good but he is an ant in an anthill at one of the dealers. I have an SD2 and unlike quite a few I am very proficient in it's use. I was trained with it in Maranello in 99 and have used it every day since. I will buy an SD3 when it makes sense to do so. Recently I sent a client to one of the local dealers for the variator campaign and after waiting 8 weeks he found out they did not have the tools to do the job. I had them. Like I said there are quite a few like me out there. Look around.
If you substitute your question with $20k for a nice new Hyundai versus $5k for a used one, you would certainly go to your independent mechanic around the corner. It makes no difference with a high end car. IMHO.
There are good independents, and there are good dealers. Frankly, the my dealer feels and acts more like an independent than a dealer shop. They are reasonably competitive on pricing with the local independents, although there is no one here with an SD-2 except for the dealer.
Every dealer mechanic is an arguement away from being an independent... Find someone that you enjoy working with (that knows what he or she is doing) and you'll be fine.