I could write a very long story about all the things that went wrong in the process of driving 1700 miles and prepping the car (as in fact I did on the UK site) but I’d rather just share the good bit that was the actual trackday. Once everything was sorted the car didn’t really miss a beat for 100 miles of being either full throttle or hard on the brakes.
I will say that I cracked 2 of my wheels in Belarus and Poland (on smooth roads with no potholes no less!) and only had 2 days to find suitable replacements. I ended up with a used (though very expensive to get) set of OZ Ultraleggeras, which I always liked anyway so a small silver lining there. I may have them done in anthracite in winter as the paint has a few scuffs here and there.
I put on new aftermarket brake discs the day before, with proper vanes, and together with fresh upgraded fluid and Carbotech XP10s I had zero fade even when I did multiple laps in a row. I did however have issues with a soft pedal and a lack of bite and feel from the brakes. It started after the fluid and disc change and I suspect a slight cock-up of my mechanic because it simply feels like there’s air in there somewhere but it won’t come out with bleeding. I ended up having to use a lot of pedal pressure and I never experienced any real “bite” from the brakes. Still I could get into the ABS with the R compound tires if I pressed hard enough so it was driveable. Just not confidence inspiring so I was braking a bit early in places.
All laps had some traffic, but the car held its own. Some 911 GT3s were faster than me, some weren’t. It’s still a heavy family sedan from 2007 anyway. Next time I will consider putting light buckets in it as the comfort seats aren’t exactly track friendly. Ambient temps were low around with a high of 10 degrees C so oil temp was no issue with highs of 126-127C. The engine ran strong and thanks to good fuel and low temps I noticed no performance degradation whatsoever as the lap went on.
The fastest lap (8:06 BTG) happened with a pretty heavy passenger on board and can be watched here: https://www.youtube.com/watch?v=u0ROivKuO7U (the first lap isn’t as interesting) As far as I can tell this is the fastest lap of an RS4 on the Ring on YouTube by a considerable margin but I wanted sub-8 and it didn’t happen. Optimal sectors added up to only 7:53 so it’s well possible for the future. This were my first Ring laps in over 5 years and the first with this car on any track.
A solo lap was recorded as well but it was the first lap at full speed of the day and a bit careful in places plus traffic. https://www.youtube.com/watch?v=NKh2Se5L1x0
I also had my buddy record a few passes on his phone as I was getting good feedback on the noise from the JHM exhaust 
https://www.youtube.com/watch?v=x_ILuW2eW20 (the last bit on the straight was about 160 MPH)
Finally, some pics.
http://www.greenringer.net/DN14/DN14_A.jpg
http://www.greenringer.net/DN14/DN14_B.jpg
http://www.greenringer.net/DN14/DN14_C.jpg
http://www.greenringer.net/DN14/DN14_D.jpg
http://www.greenringer.net/DN14/2.jpg