Just replaced chain and sprockets a couple of weeks ago on my G5. Had clocked up 7800 miles on the original standard chain and it was at it's max adjustment. Have to say, suspecting the OEM chain to be an el-cheapo , I was surprised that it had lasted so long. Replaced it with an o-ring chain having gone up from a 17 to 18 tooth front (from Hitchcocks) and replaced the rear drum/sprocket direct from India. Was not initially impressed by the look of the rear drum/sprocket as it was not as well machined in the drum as the OEM . However, had never been happy with the rear brake , to the point of not feeling secure when braking. Now the rear brake WORKS , oh does it work.
Now to see how well the new chain lasts. Not that I am disappointed with the original as most of my past experience has been with very fast Ducati singles ridden much harder and under more extreme conditions than northern California throws at me.