Also Matt
MIDI files created by BIAB will already follow tempo changes in a DAW. In your case the external device will follow changes to the MIDI data from the DAW.
If you also used Realtracks in the song and drag those out as wav files they will now drop into the DAW with the tempo data and you should be able to then make further changes to the tempo in the DAW and both the MIDI and Realtrack renderings will follow correctly together.

How I typically use it is to develop the song in BIAB then play the song with my own performance either with or without the BIAB files in the DAW then map my natural tempo to the Realtracks thus the BIAB musicians follow me perfectly.

https://www.youtube.com/watch?v=SIQ_q1sP9JQ
Here is a video of me doing that prior to the patch. I manually set the Realtrack tempos for it to work, now it's automatic.

Hope that helps people see the possibilities.


Studio One (latest version), Win 11 23H2 , i9 -10940X 3.3 GHz, 32GB Mem, a 4K 40" monitor, PreSonus Studio Live III Console as interface/controller. secondarily test on Reaper, Cakewalk, and S1 on Surface Pro 3 Win 10 (latest versions).