Which is an unambiguous sign that you basically prefer stereo spot mics, too. 😉 What do you expect from a mono mic that a stereo setup couldn't pick up?
Actually, I don't know. :D I'm happy that the Silent Stage instruments were recorded that way. A mono microphone as MIR Pro's spot microphone won't have the same sound and stereo width.
I was only wondering, because in these "Hollywood" libraries the spot is in most cases mono. Having a main microphone mixed with a mono spot does indeed sound different than having a stereo spot. Reducing the stereo width in MIR Pro won't give me this combination of wideness and closeness at the same time; MIR Pro is a good compromise between the two.
To make a long story short: Apparently I like both approaches.