[zakco]

For me, it's rare that I can just deactivate all RTAS plugins and not have the working mix completely fall apart, so I usually bounce a quick mix (or a few stems), save the session with a new name, deactivate (or remove) all tracks except the mix and the new tracks. Once I'm done the overdubs, I just re-open the old session and import the new tracks. Not exactly elegant workaround but it works....