I'm now selling my GS as I just could not get the right seating/grip/riding position - I tried 4 seats and two sets of risers, but just could not get comfortable, and that is so important if you actually want to use the bike.
I'm currently selling the Corbin duel seat I had last - but I've answered this in posts before I ever decided to sell the bike, so it's not a sales ploy. In order of comfort I found them in this order:
1. Corbin
2. Sargent
3. Touratech
4. BMW original seat
Not too surprisingly they go in that order prices wise also, they were all different, I went form one to another slowly going up in price, but still did not get the comfort I wanted, so have just bought a K1600 GTLE. This is not a reflection on the seats - we are all built differently, so you may do as I did and try a few before you get the one that is right for you, just try to get them second hand as if I had done this with new seats I'd be down the best part of a grand instead of perhaps £20 a seat plus postage?
James