Hi there
I've seen these before, and while in theory they look really good idea, I'm not convinced. When I worked for papers and agencies as a photographer, I always had at least two bodies out and ready to use on an assignment. Often you need to crawl, run, climb, kneel etc. I found it easier to be able to put the cameras down, back in a bag or pass them to some one. I'd imagine if you're decked out like a christmas tree it would be a PITA to get the gear off to be able to move fast.
Also it looks a fairly bulky affair. If you're a working photographer you're always conscious to reduce the amount of bulk and weight you carry.
I think a good wide camera strap is all you need. The best strap I ever had was a freebie given to me by Nikon at a sporting event. Even though I used Canon cameras I always had it on my main body.. much to the annoyance of the Canon rep. I used it on several cameras until it got stolen (unfortunatley with a full camera bag too.) Perhaps Canon listend as the last two cameras both had good wide straps tha don't dig into your neck.
Just my 2 Euros worth.
Gareth