Hi David,
there's nothing wrong with it per se . You know the old saying, "If it sounds right, it is right!". But read on. ;-)
The reason that you aim for that solution might be very well solvable directly within MIR Pro, though, by selecting a Main Microphone settings that gives you more width, and/or by adding a Secondary Microphone with capsules aimed towards the side- or backwalls of the selected Venue, or by choosing a different Main Microphone position in general (... most likely one closer to the source).
The answer to your second question is quite obvious: You can't change the width of a signal with a processor that's working _before_ the actual sound source, routing-wise. :-) Using the Vienna Suite's Imager on the dry Bassoon signal will widen the instrument's sound itself, but this effect will get lost to a large extent anyway as soon as the signal enters MIR which takes care for its position, width and rotation itself, by definition. The reverb can't be affected by the Imager like this.
HTH,