I've had issues with usability with all the left hand controllers I've tried. I liked the NAV but I tended to drift left and right instead of running a straight line.
I finally decided to make my own controller with all the buttons where I want them, and heavy duty enough to take some serious punishment.
I'll the buttons are custom placed after 2 prototypes, so I can use them by bumping or tapping without losing my groove. Hope this is helpful for some of those still trying to find a good setup.

I used a IPAC2 controller board, with a 2 button joystick as primary and a competition Happ stick for Dpad. I just played around with it for a little and I think once I get used to my new button mappings I'l be able to do some damage

lopaka