On my previous bike, I had gore derailleur cables. Shifting performance was always excellent but after about nine months I had to replace them because the liner was damaged and allowed debris/water in. Now granted, this was most likely an installation issue (I did the installation and myself) but nonetheless it was an issue.

My new bike has plain campy cable with no liners (it's a used litespeed w/chorus 9-speed). I just squirt some lube in every now and then and don't sweat it. I think I'll just stay with the cheap stuff for now...