So I've done about 6000km in the new seats, here's my observations. First off I'll give the coverings an 8.5/10. There is an imperfection in the right drivers bolster that I didn't look for when I picked it up and very slight variation in the puffiness of the diamonds between bolsters and flat sections.
If you sit in the lowest driving position, you will notice you can't get quite as low, I was worried to start with, but the foam has softened nicely and I'm used to the few mm higher that I feel I'm sitting. Lumbar adjustment range isn't as pronounced. Front passenger seat does not fold forward as far. My favorite board is now a pain in the arse to get in. If you really want to be locked in or are on the smaller side, get some alcantara/suede on the back at least. If you want absolute perfection and no custom layouts, buy mint seats from HSV's. Overall, I wouldn't change my configuration. I did 4500km in 5 days of driving and had no pain and suffering, they were really comfortable. I did 5 minutes in the original Redline seats and couldn't wait to get out of them! In summary, expensive but worth it.