I swapped my Naza out of an F450 and put it into a TBS Discovery but then put it back again. I found that the CoG on the Disco made it toilet-bowl like a ***** and it required a fair bit more setting up and mucking about to make it fly correctly.
As others have said here, the biggest reason for the toilet bowl effect is the NAZAs lack of ability to compensate for "magnetic declination" - that is, depending on where you live on the planet, your GPS puck needs to be rotated a certain number of degrees left or right. It could be a little or a LOT. Last year I learned of this when I noted that my quad wanted to fly on an angle - like a car with bad alignment. I am in New Jersey, so in my case twisting the puck 12 degrees to the left fixed it. Look at the map below for the adjustment YOU will need to make. This one is for the USA. If you are somewhere else on the planet, here's a page that describes the phenomenon more authoritatively than I can, and gives a calculator...
http://ngdc.noaa.gov/geomag/declination.shtml
Note that this map changes a little each year!
I found this bit of info which summarizes the fix: "...If your location has a
POSITIVE declination then turn your GPS to the
RIGHT the number of degrees of declination for your area. If your location has a
NEGATIVE declination then turn your GPS antenna
LEFT the number of degrees of declination for your area..." That line
came from this page. The part that talks about magnetic declination is halfway down the page. Take a look! Best of luck.
Another question re your TBS setup: In the assistant software, did you plug in the distance from the NAZA to the GPS puck on the X, Y, and Z axis, in cm? I don't know what the impact is of NOT doing that is, but it can't be good.
