RobtE30, The DA 9S group falls into the 7700 series, IIRC. The 74XX group series can go back to 6S through the 8S. When and if you change the RD don't buy an 8S unit. They have a different pull ratio to just about everything else, friction shifting will work.

An older set of DA 9S hubs will take 7 (w/spacer) to, as I understood also, the early 10S cassettes.

Brad