So for the first time (I think) I can say that I'm glad some internet posts got inside my head. I kept reading how people were changing shift/brake cables and housings with alarming frequency-- once a year, every 2k or 3k miles, etc. So I went back and checked the sheet for my Ritchey... the housings are original from when I built up the bike, but I did change the inner cable when I put the HRD levers on. Sooooo uh.... 15,800 on the housing, 6,400 on the cable.
I just changed it out with a Shimano Optislick cable and housing, and... wow. It's like butter. I'm probably going to be overshifting for the next few weeks. In related news, 7,900 miles on the Jagwire Elite Link on my Cervelo. Sigh.