Strange coicidence, but I was opening up the final drive on my 3000 mile GS last night too! I left it hanging overnight for oil to drip out, just need to find some moly 60 and then I can put it all back together.
Anyway, my splines looked nothing like yours - mine were a bit lacking in grease, but were in what looked really good unmarked condition. Although mine is only 3k miles, it is still 2.5 years old.
I believe it was very well looked after for its first two years - it came to me last august spotless with less than 1k miles and looked like it had never seen a raindrop, so that might be part of reason. However, since then it has lived outside and been riden through a britsh winter and that seems not to have had an effect.
PS did you buy your x0 oil on line, or find a shop. I am about to use a generic fully synth 75w/90 from a local specialist oil blender unless I can easily get the brand name!
Darren