i think if you save a RB file as a seq file its 'frozen' anyway - RB plays audio files on each track just as they were when you saved the seq file. even when the tracks are midi i don't think seq files regenerate so the lag you used to get with BIAB as it regenerated doesn't - and didn't apply.

however when you generate a new RT on a new track it might be nice to have the faster gneration of all cores working at once although the wait has never been a problem for me.