Agostino,
like pointed out in the manual, _all_ signals within MIR are handled as Ambisonics stream. This means that the dry signal can be put in _exactly_ the same place as the original direct component in the impulse responses. You can easily test this yourself: Select the Direct Only-mode in the Output Channel and move an Icon on a Venue`s stage. You will be able to follow its position almost pixel-by-pixel ;-). This is even more exciting in surround, BTW.
In other words: Yes, you can forget about anything panning-related when working with MIR (with the one exception of panning inherent to any true stereo-components in an original signal, like the bass-treble spreading of a close-miked Grand Piano).
HTH,
/Dietz - Vienna Symphonic Library