I think your real decision is whether to let BiaB export as wav or have Reaper import it to wav.
The only difference is which one does the conversion.

Either way I think you end up with a wav file(s) in Reaper as far as size goes.
Reaper should adjust any imported audio to the project settings (most likely wav) ..
so really 'six of one VS half dozen of the other' in my experience.

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