I would imagine coaxial speakers wouldn't be any different than an individual driver when measuring near field (i.e. <12" ideal). You have no other drivers offering their off axis contribution, so I would go with the under 12" and use a gate that takes the low frequency limitation into consideration.
Also remember to keep the mic boom out of the way as much as possible to remove reflections.
brucek
Also remember to keep the mic boom out of the way as much as possible to remove reflections.
brucek