If you repoint the Altiris Agent from the NS which has Recovery Solution to another one (a NS7 box I would guess) then you won't be able to manage the Recovery Cluster anymore. The RS server needs to communicate with the Recovery Solution components installed on the NS6 server.
This is the same "chicken and the egg" scenario we're facing; how to upgrade/migrate our NS (and Recovery environment) to 7.0 and redirect both the clusters, RS server, and RS clients to the new environment without interruption in snapshot or recovery, and in a timely fashion? The end-user machines don't care too much; they'll keep using whatever configuration they received the last time they updated configuration, with regards to schedule, exclusions, etc. it is the servers that get a bit tricky. Haven't expended much effort in testing this so far, so unfortunately that's all the detail I can provide for now.