I agree with all of the above. The other issue with EMT is that it wobbles a lot. Take a 10' piece of 1/2" EMT and hold it in the middle and shake it and see how long it takes to stop moving. Now use a set screw coupler and add another 5' and see how much it flexes at that joint. Also, that bottom plate has more than just one hole in it. It's got four mounting holes, as well. Will dust enter through them and collect in the dome? (Probably yes, eventually)
I don't see the bottom plate really being an issue (I'll believe people who have used them, considering the specs of Avigilon's H3 domes say the whole body is plastic) so much as the conduit used, aside from it not being how the manufacturer recommended.
All that being said, I can understand why they did it this way, and I don't really blame them, because the pendant mount bracket uses 1.5" NPT thread I think, which is GIANT for this application. And I believe that bracket is for the outdoor dome only, which is a big price jump from the indoor model.