I think you'll find the difference with the clutch issues is that the more modern friction materials are more forgiving with the synthetics. Those that are using synthetic without issues are probably those that have replaced the friction plates in the clutch.
The older ones HATE it.
The older ones HATE it.

(Regular 20/50 dino oil.. I have a personal favorite but won't get into that) I change the filter every other time.. most of the time.. I think. I change the drive gear oil every year.. or other year.. or when I forget to put the fill plug back on and spew the contents all over me, the bike, and the highway, or when the middle drive plug falls out the bottom going down the highway. That reminds me....that was a couple years ago. I need to change it.. Maybe. 
(Sold back to Maximan)
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