Thanks for the feedback, Daniel.
We did take a look at the Order Management app from the forge. It is reactive, but it's not using BPT.
However, I do see some others that appear to blend both that we can look at while we do our own PoC.
Of note, I just found these release notes indicating that the Human Activity Destination property was added to Reactive Web Apps starting with v11.8.0 - which is not mentioned in the documentation, save for a small anecdote in the sample app. Not really a concern for us as we're using custom task boxes; but worth pointing out in case others find their way here.