Hi Dav,
I understand that you are under the impression there is no difference between 4k and 1080p footage when viewed on a 1080p display. Unfortunately, this is incorrect.
I think there are two things worth noting here. First is an explanation as to why there is a real, measurable difference in quality between the two:
The second is, I feel that if you are telling people misleading / false information like that there is no quality difference, you are doing them a disservice in their purchasing decisions. It's ok to not know stuff. But if you don't know stuff and confuse others who are trying to make purchasing decisions, that starts to venture into 'unfortunate' territory.
If you are looking for the Phantom that makes the best quality videos, it is the Phantom 3 pro in 4k mode. Objectively so.