It's becoming pretty clear that my Chainglider/Surly SS/KMC X8 setup is an economy measure! Yeah, I know... On my previous setups, whether open derailleur or cased chain hub gearbox bikes, I would go through three cheap chains and Nexus cranksets and Shimano sprockets in the 4605km my first KMC X8 lasted, with no noticeable wear to the Rohloff sprocket or the steel chain wheel. So, because I'm heavy on transmission gear, even though my motive wasn't saving money but convenience, I'm ahead under 5000km. (In part because I bought a batch of KMC X8 at a deep discount CRC sale for just about the same as cheap Shimano/SRAM chains had previously cost me.) I would expect the rest of you, who're all apparently lighter on your transmissions than me, to see financial advantage in a Chainglider at around 10,000km.
My experience leads me to conclude that it wouldn't be smart to cheapen your chain or chainring when you buy a Chainglider. The better the gear that you cover up, the greater the benefit. Bit counterintuitive, but I think the soft Nexus ali was grinding away fast enough to destroy the cheap chains I had, even inside the Dutch chain cases, whereas my current Surly stainless steel chain works much more happily with the quality steel of the KMC chain. There's less to grind internally, and very little gets in from outside through the Chainglider's defences.
In this perspective the Chainglider is starting to seem like a bargain.
Andre Jute