I heard of its slow response (very obvious) due to slow electronic processing inside from people playing 1:10, even though it is using 2.4Ghz for sending signal.
Mini-z requires very fast response (think of the frequency of turning your steering wheel and compare it with other RC), so I guess EX-10 seems a very good choice. You can wait for the newest version (arriving in Jan? soon?). There are people using 3PK or M11 who have their modules modified and they are equally happy. I have also seen someone modifying a 4PK for the mini-Z. What a sophisticated player is he! (because he can't use the 4PK back onto other RC!)