I am aware of several issues with said dealer which I won't go into as they were shared in confidence, but I am not alone with my R8.....actually I have got lucky.
Anyway I have her back tonight singing like Pavarotti and it has helped me form a more objective view on the McLaren test drive today too. One thing is clear, McLaren's engines, all of them, don't get close to the charisma of the V10 in my R8. V8's with a flat plane crank and 2 big turbos are never going to, removing the turbos would not do that either I suspect. Sure, epic performance, epic torques but lacking the sheer noise and event of my V10.
It really is the finest engine I have driven in a car, not the finest ever I am sure, but really very very special.
All I can truly hope for you now buddy is the car is well behaved for whilst it remains in your hands, because to me it sounds like any issue becomes a nightmare to fix, but good work on finding a specialist.
I think most people know of the utter poor service and warranty work I got with Bristol Street Ford, you felt like a number and they did not give a toss about you or the car.

I've since changed dealers, luckily even closer to me in Congleton, a family owned dealership and wow they really are a 10/10 garage.
When my rear caliper seized they had it booked it, pair disc, pair of pads and new caliper on order and I dropped it off and within a couple of hours I was called to be told car is ready.
They even let me use their alignment ramp and alignment sensors/computer to align and setup the car as I wished, must have being on it for 2-3hr, they charged me £60
My recent warranty claim was for right hand side catalyst. I noticed the car felt slow, so plugged in my gauge which monitors knock and low and behold the knock sensor was going positive on gear changes but it was false knock as the timing was way too low and if it was knocking the amount the gauge was reading (+6.00) I'd hear it. So I had the car jacked up at home and right hand side exhaust sounded full of metal.
Went to local dealership, they agreed to get it on ramp there and then, rubber hammer and yep noise seems most present on right hand catalyst at flexi joint, so they agreed to order parts in. Next day they call to say gaskets/bolts arrive but Ford Germany cannot even provide an ETA for the catalyst. I said I have one from my mate who fitted headers, as such can you fit me his and when the brand new one arrives call me and I will get it? They said yep, they did same with rear brake disc when they fixed my seized caliper, hence I have to brand new brake disc in my garage. So they got my friends none rattling cat fitted, this time I requested a car, they obliged. Three hours later they call me, all done and the exhaust is confirmed as not rattling.
Collect the car, knock sensor is back to only reading negative and car running the full 30+ timing it should. I've found a good dealer and in short it makes the whole ownership experience vastly better!
Onto best engines, I will agree, the R8 V10 and the 7.0l from GM are the two best engines I have ever experienced, thats not to say others are bad, but those two were extremely special.