Clientupdate minimum version

Hello,

I couldn't find any documentation regarding this, but is there a minimum version for the clientupdate to work properly? I have just upgraded my server to the RC for 4.2, but I am still using the BigBrother client and deploying the client to my servers step by step, and would prefer not to have to deploy clients again once a "stable" version is released.

Thanks,

Jeffrey Chandler