I own a zidoo x9 and since x9s is a rt1295 kodi will not be support by kodi. For more information look at this page http://kodi.wiki/view/ Android_hardware and under rt1295 you will see append 1. In other word kodi will be again under zidoo team patch and developpement. Remember x9 can only use a special xbmc version 15.1 (still full of bug) and there no further developpement.
There is already Marshmallow firmware for the RK3368 chip used in Zidoo X6, so it will also get stable Marshmallow firmware in a few months.
I don't see a big "PRO" having MM (android 6); I think that A5.1, for this use (TV box), is "enough". For sure MM is better for smartphone and tablets, also for security reasons. But, anyway, there may be some potential "CONS" for X9S, having RT chipset, even if newer and powerful. The support for apps (Kodi or SPMC) could be (again, like RK) all on Zidoo team. But the biggest CON (for us) could be the support from ZTeam on X6. They have now a plenty of new boxes (X5, X1 II, X9S) to develop and maintain and X6 could be let it down ....
