I have the Park 480 on my Mini Pulse, and with a 11x7 slowfly I was getting 10 minutes, then the ESC was shutting it down. So with the 12x6 I would assume you would be around 8-9 minutes or so. But 3D is a different application than the Mini Pulse. And the Funtana X is just a little heavier. Those two differences may be playing a role.

I switched to a 10x7 Slowfly and now I am getting 12-14 minutes depending on how hard I push it of course.

Maybe try coming down to an 11x6 and see what happens.