It seems like that there are several different manufacturers offering aluminum monitor bracket upgrades for the P3 transmitter.  Is there any site offering reviews of the different brackets, or a thread here discussing them?  What's the general consensus on the best one?  If I can find a buyer for my Canon 5D, I may be getting myself a P3A sooner than expected.

If your talking about the Pro and Advanced the stock one works pretty good. I was going to get the metal inspire one since I'm using an iPad Air and it's pretty heavy on the stock mount BUT I just torqued down the knurled knob and it works fine. There is wobble but it holds the iPad good enough. Now if you plan on doing a follow me and running with an iPad then that's a different story.
One day I'll get a metal mount but I'm good for now.

The Inspire 1 tablet mount is an awesome upgrade if you're planning on using any kind of tablet. Here's a before and after when I installed mine:

http://www.phantompilots.com/thr ... -tablet-mount.42864

Some people say tightening down the stock mount works, but it'll only loosen over time. And, even when tight, the mount still give a bit since it's made of plastic.

The Inspire bracket is perfect, I have my ipad pro mounted to my P3P controller and it's solid. Others may work if you want to experiment.