This looks like a very interesting rig (R Series Strap). It reminds me of the tried and true M-4 tac sling. The concept is not a new one, and it will be favored by some photographers more than others.
Nothing to do with the strap, but with personal opinions.
As for me, I am going to get an R1 for a couple of reasons. First, in some circumstances I could use a backup strap for the main camera. So I don't need to crowd the standard strap slots, I can just have a backup to keep the camera from falling to its doom. Second reason is -as mentioned earlier on- it looks like a really comfy way to carry a tele lens, along with your cameras (when you can't or won't use your bag). Sports photography is a great example, you have two bodies, and three lenses. 16-35 and 70-200 mounted, but say a 300 3.8 or 400mm hanging on the side. You can make a swap without any effort.
I have been using quick release straps for safety reasons most of the time, given the last chopper ride -keep your cameras inside the aircraft at all times-, and a long climb up a tower (where the cameras were made available to me via rope and pulley rig, with both 1Ds and $4000 of lenses attached to the straps with no backup, I almost broke the record for altitude barfing). On their way down, I was the one securing them, so I worked aorund the quick release.
Again, it's all in the use of the camera. If I have to deploy a fire shelter, life sucks. Cameras get out in two simple moves (one per camera), allowing me to drop pack and deploy safely. I am suppossed to do this in 20-30 seconds (which despite practice, I am nowhere near). With normal straps, I'd be one unlucky photographer in case of emergency.