Only other problem I have with BMW seats (more design of the mounts than the seats) is the fact they always seem to pitch you forward making you slide into the tank.
On the 1150gs and the last 1200gsa tc I put spacers under the of the front mount brackets which raised the nose of the seat, On the LC I made a set of offset replacements for the rubbers which did work but I was looking for a more permanent solution.
Due to the design of the tank you cannot lift the front mounts with spacers as they will foul the tank centre panel, whilst looking online I found that the r1200rt lc uses the same front mount for the seat as the gs and gsa but the actual bar that the tank rubbers fit onto is different.
Picked one up secondhand for £10 off e bay, if you look the one on the left is the original gs/gsa fitting the one on the right is from the rt model, once fitted it lifts the front of the seat just enough o stop you sliding forward on braking , it is slightly more difficult to get the flats of both feet on the ground when stationary but once on the move it is a much nice seating position