Hi Frank,
the answer is straight-forward: The validity of an Icon's position is calculated by the coordinates of it's "body" (i.e. the inner circle), while the actual IR's are triggered by the handles of the outer ellipse (which is also the place where the left and right channels of the dry signal will be situated).
So - if you use an Instrument Profile which allows for highly exaggerated stereo settings (General Purpose Profiles are a good example), then MIR will try to interpolate the IR-paramters for any "off-site" position, as long as the Icon itself sits on a valid HotSpot. Although the Ambisonics-format allows for very good interpolation between individual IR-positions on a MIR-stage, it can't move walls 8-) ... in other words, technically the interpolated IR-sets derived from positions _outside_ th HotSpot-area will simply be wrong. OTOH - as long as you like what you hear, nothing is hindering you from using these settings as an effect!
Kind regards,
/Dietz - Vienna Symphonic Library