I have a 2010 Bianchi Vigorelli I bought 2 years ago, probably around 2,000 miles total on it so far (I know, slacker... ). I measured my chain recently and found it was pretty worn, both with the ruler test and using a Filzer chain wear gauge (appeasing both sides of that argument). With the Filzer gauge it falls right through to the 1% mark (here's what the gauge looks like: http://www.amazon.com/gp/product/B004FRTJ0Q).
I took the bike into the LBS for a tune-up/"drivetrain overhaul" expecting them to replace the chain. I got the bike back, very clean looking, same worn chain. When I called to ask why they didn't replace it, they told me their philosophy is that the chain and cassette wear together and unless you are experiencing shifting problems or chain skip, it is best to just keep the chain/cassette clean and lubed until you replace them both. The drivetrain overhaul involves them taking apart and cleaning the chain/cassette/RD, etc...
Now, I can certainly see the logic in what they are saying, but it seems like this sets them up to replace a lot more cassettes (and possibly chainrings) down the line...is their repair philosophy complete BS or do any of you also prescribe to the "if it ain't broke don't fix it" school of thought?
Wondering if I should just slap a new chain on and deal with the possibility of skipping until the new chain wears to match the cassette teeth or just leave it and replace both chain and cassette when I have reason to (chain breaks, skipping, bad shifting, etc...)
FWIW, I took it out for 60 miles this weekend on a ride that used all gears and experienced no issues whatsoever.