Due to a car breakdown, I am still waiting on a musician to show up for sessions today, so am studying Vienna MIR Pro (I found a preliminary copy of the manual, which I didn't know I had).
Turns out this is quite workable within Vienna Ensemble Pro, so I should have taken that tactic first instead of jumping in the deep end by first using it on an Aux Channel inside Digital Performer.
There is quite a learning curve, for sure, and incredible power.
I do notice, however, that most of the placement is left to the user. Fine for later in a project, but too slow for early work (although I will eventually create some templates).
Therefore, I can see how MIRx will greatly accelerate early production stages as well as help when just trying to quickly verify conceptual changes to arrangements, as often those choices are hard to validate without a better idea of final mix context.
Looks like I'm going to splurge on MIRx shortly...