I got my seat covers from KHM 2 years ago. Very happy with them. I actually stopped by in Esslingen on a trip through southern Germany and chatted with Mr Mayer, owner of KHM, before I bought them. Highly recommended. The many types of leather they offer are worth seeing, touching, and smelling. Plus Esslingen is a very pretty little town.
I went with type 10C, which is called Roser reproduction. Roser was the company that made the high end leather seats for Mercedes in the 60s. Mr Mayer said the leather is from German cows, oh well. But the leather is beautiful and I really like the smell, which it still has after 2 years. The GAHH covers I had before didn't smell at all. Gernold Nisius at SL-Tech installed the covers for me. They look beautiful. I am very happy with this purchase The covers look even better after I treated them with Elephant leather wax, as recommended by KHM.
If you don't want the hassle of buying them in Germany, Gernold mentioned that GAHH has a special "Oldtimer line" of their covers, which are similar in quality.