Although I use MIR, I do also use the Vienna Suite reverb as well. If I need to put a vocal on to the orchestra, I don't need to route the audio across the network to MIR and back again, I just use the Vienna Suite reverb, and as I can pick the same room, it blends perfectly well.
Most vocal performances are recorded reasonable dead centre, so you don't need to move the singer around the room. (this applies to most audio recorded solo performances as well, if you need one in the mix).
Also, the hybrid reverb is really good for adding that something extra to drums etc