I would check my splines IAW the video below. I wouldn't worry about lubing them if they're good.
Worn splines through starter hole w/ video
The HES on the R1100S is a little more stout than the old oilhead HES. I might consider carrying a spare, because they're relatively small and light.
I wouldn't be concerned about the final drive, but if overpreparation is your thing you could carry a spare big bearing and seal.
I would consider swapping out the brake lines too. There have been documented failures of brake lines as these bikes age.