Steve,
We are running CCM (3.3.3 now but have run 3.0.9, 3.1.3, 3.1.4 and 3.3.2) with an iSDX-s that runs 7.1 software. We use the iSDX to provide DDI numbers for 50 users on the CCM side. We can call forward transfer, etc. from iSDX to CCM and from CCM to iSDX.
We run an e1 card and use a q.931 trunk from the DLI card in the iSDX into the back of a 2611 router. We do loose some functionality though. We have no CLI passed through, and use unity for UM on CCM but a seperate VM for iSDX.
If you want some more info off line then drop me a mail.
Regards
David