Ok.
First, I need to apologise for the lack of scientific data and results here.... as I didn't really do anything other than experience a bit of a bottom-clenching moment whilst using the Argtek aerials....
In a nutshell, the Argtek aerials didn't give me much more confidence than the standard setup if I'm to be perfectly honest. I experienced signal drop-outs at what I would consider to be short range - and certainly not very far as-the-crow-flies. The area is pretty low in RF interference, so there was no excuse there either.
As far as the DBS goes, they're worth every penny in my opinion. So much so, that I will be performing a permanent modification on my return; drilling the controller case, and allowing the connectors to sit with less stress and constriction.
The DBS allowed me to send the Phantom far, far away.... so far, I had to search for it with binoculars, but at the same time streaming back a clear picture to my handset.
I'll probably repurpose the aerials for my wifi router at home - or stick them on eBay. They'll be fine for someone else, I'm sure.
Anyway, here are some photos of today's flight at San Bay, Ardnamurchan (Western Scotland). The weather was fine, albeit a bit blustery. The P3S performed amazingly in the wind - very impressed with the stability and power in the motors.
(video to follow.... the internet bandwidth isn't fat enough for an upload at the moment, I'm afraid)