I use the M-S mic technique frequently for location classical recording.

From perusing the manuals, it appears that OctaMic II does not directly supprt the use of an M-S matrix in any mic input pair.  The Micstacy manual has a paragraph on M-S but apart from the fact that it is only operative on the digital out, it is not clear, particularly from the block diagram,  if the M-S matrix operation is introduced independently on each pair of channels, or as a global command - ie.,  all channels pairs are either X-Y or M-S.

(Alright - I'm in my sunset years and my eyes as well as my ears are not as good as they used to be  - just quote me the page number in the Micstacy manual where I've missed this bit of info .... )