From what I understand, and Dietz correct me if I'm wrong, MIR Pro will run "on top" of Ensemble Pro. It will combine the mixing concept (including inserts, buses, sends, etc,) employ LAN, and the rest, but allow you to create and mix within space. In other words, it's like combining the live room, hall, stage, etc. with the control room. You will be able to "mix" the performance, i.e., the ensemble and the environment, as an integrated whole. Best not to think of MIR Pro (or MIR) as a reverb, then, bc it is not. Having control over the environment is much more. Add algo verbs for sweetening, sound design, etc., but it shouldn't hold the same pride of place if MIR serves as the spatial foundation. You can add a nice lush algo to a great sounding hall but you wouldn't want to overstep and lose the hall (scoring stage, cathedral, etc.) for it. (You can, of course, but MIR wouldn't be necessary to that particular project.) I'd imagine the algo part of Hybrid Reverb will be employed in MIR Pro for this exact purpose. If you have a Bricasti or the like, even better. One's a great reverb and one is MIR Pro. I'd imagine this combo will sound amazing if done well. Of course, the convo will be redundant (and inferior) when using MIR (Pro), unless you are using it for tonal purposes (such as FORTI and SERTI).
This, at least, is what I've gathered from the MIR Pro rumor mill. Any corrections or new info is most welcome :)
Best,
Mike