Why Mikrotik choose different polarities for different types of antenna?
For example, in the SXT and SEXTANT:
CH0 Horizontal
CH1 Vertical
see manual http://i.mt.lv/routerboard/files/SXTug.pdf at page 5 says to disable Tx Chain0 for use in Vertical pol

while for the BaseBox + Dish
CH0 Vertical
CH1 Horizontal
see manual http://i.mt.lv/routerboard/files/MTAD-5 ... 130311.pdf at page 3

Now suppose, that I have a Dual Pol AP Sector where I connect many clients from different distances (2,6,10,20 km):
I would have an inconsistency between the various Chain using different types of antenna.

Now the question is:
doesn't change anything if the polarity is reversed between AP and Stations (bad throughput, bad behaviour)
or
if I connect 10 antennas on the same AP with chain/polarities corrected and another 10 reversed?

"Reverse" antenna do not exist, simple MIMO is MULTIPLE antenna...