I know it's late reply, but one of my colleague having CX9 since 2009 oe 2010 and he reported of some transmission issue that has been dealt in warranty with Galadari without any problem. After that, there is no issue so far. It seems in early models of CX-9 some reported transmission slipping and transmission fluid problem was there but after 2011 none reported so far. So i guess if you planning to buy 2014 model it will be good to go.
You can take your car to mussafah area in abu dhabi and there are few good workshop i seen last year. I am from Dubai but been to musaffah two times and seen good mechanic there. May be you can call few workshop from below link
http://www.mazdadubai.com/workshop/general-purpose-workshop-garage-abu-dhabi-t288.html