I've been using Campy Chorus 10-spd brifters with SRAM 10-spd RD (both X.9 on the tandem and Rival on my single) for a total of about 10K miles. The shifting is near perfect, even though the Campy pull is slightly non-linear. Total total cable pull is almost identical. I know DaveSSS expresses skepticism every time this comes up, but it does work very well. I was put on to this by my LBS; apparently a number of Cyclocross racers use this setup, generally just with one chain ring. I do really like the Campy shifters especially on the tandem where we do a lot of shifting.

I first tried a Jtek and wasn't completely happy with the shifting. Then I inadvertently tried a SRAM X.9 9-spd RD and this definitely doesn't work. The newest 10-spd RD, as I indicated above, are a near perfect match. For my triple conversion I needed to replace my Rival RD with and X.9 to get the desired chain wrap capacity; the Rival would have been max'ed out with the 12-27 cassette and I wanted the option to put on an 11-32 (or larger) RD in case of a particularly nasty ride.