OS .46AX is the way to go. I have one and I trust it to my life, I have well over 50+ flights on it, it has never quit, never spit or sputtered on me, I have it on an Extra 300, and the thing is heavy, and it pulls it vertical for a VERY long ways with a 12x4.

EDIT: I have some expirence with TT .46Pro and I can tell you its lacking, the OS is way more powerful.