Any time you switch back and forth between the two (RB & BiaB) you risk losing some feature the other had.
They are two different programs.
As mentioned, the workflow for many of us is start in BiaB, then move to RB to refine .. going back and forth has many trade offs, and most long time users realize you do 'X' in BiaB then move to RB to do 'Y'.

Also mentioned above is that RB doesn't do the Bar Based lyrics. It handles lyrics differently (and in some ways more accurately).
So I don't think you can move bar based lyrics from BiaB to RB. Maybe someone else knows different.

I do not work here, but the benefits are still awesome
Make your sound your own!