Well I don't have a GS I have the R1200R lc, according to the BMW service schedule in my owners book it's just a normal main service so shouldn't hold any surprises.
It's surprising if you compare modern BMW service costs with other makes, particularly some Japanese stuff or a well known British brand then the service costs for our bikes are quite reasonable. At least it's not eight hours labour to adjust the tappets and sync
throttle bodies like I was quoted for a Triumph tiger explorer!
cheers
tony