2b,
Many users here have the following workflow:

1: Create the initial song in BiaB, chords, melody, structure, style etc.

2: Import it into RealBand for fine-tuning, adding additional tracks beyond BiaB's track limitation, regenerate only certain sections of the song rather than the entire song as BiB is limited to, etc.

3: Optionally, export the RB tracks to a different DAW for final mastering, mixing etc.

Many times, there's no need to go past Step 1.

So I think that many users start with BiaB, and take it to RealBand if required. Some might skip Step 2 all together.

Others will chip in with their work flow.

HTH
Trev

BIAB & RB2025 Win.(Audiophile), Sonar Platinum, Cakewalk by Bandlab, Izotope Prod.Bundle, Roland RD-1000, Synthogy Ivory, Kontakt, Focusrite 18i20, KetronSD2, NS40M Monitors, Pioneer Active Monitors, AKG K271 Studio H'phones