I've said this in other parts of this forum, but here goes.
I think you're over-thinking things. The DJI Phantom is a consumer-grade entry-level quadcopter. It is the first 'serious' quadcopter available to first-time RC pilots, which is why it continues to sell so well. Hundreds of thousands have been sold since the beginning of this year. However, the RC quad hobby for the past few years, particularly since the advent of LiPos and advanced flight controllers, has been the domain of 'hobbyists', people for whom soldering, sawing, riveting, and just building things generally are accepted as being how things are. The first reaction of those people to the Phantom is 'how can I upgrade this', whereas the newbie says things like 'how can I use this for aerial photography'.
The Phantom is a small 330-class quadcopter with a plastic shell as its primary structural component. We know the shell reacts very badly to Loctite, that larger motors quickly cause fatigue cracks at the ends of the arms, and that the stock propellers exacerbate rolling shutter effects because they are made of the same soft plastic as the shell, and therefore flex a lot. The Naza-M also has some fairly seriousl limitations as well. It's not a 550, it's not made of carbon fibre or aluminium, and its performance envelope is noticeably conservative.
If you want a stable aerial platform that seriously kicks ***, buy one. No matter how much you might tweak the Phantom, it has inbuilt limitations that will disappoint efforts to turn it into some kind of monster flying machine.
Michael McBain
Melbourne, Australia