There is no better, just

First why the RS-7 version? Simply because this strap is comfortable and free of bulky pockets. And not besois extra strap that goes under the arm: it does absolutely worthless otherwise interfere. The two sliding stops on the strap, are ample (check out the videos on the manufacturer's website).
But the system itself: what a revolution!
One can carry his equipment without choking or sawing and chopping neck in 1 second comfortably and accurately.
Before I had a strap Lowepro Transporter that was still better than the Canon original straps, but I still recovered from this small pouch purse strap Velcro (thin) in which I put one CF card and trapping battery.
Yes because now I have no excuse (weight and size) to not let the grip mounted on my EOS 7D with my shoulder because 100-400L EF or EF 24-70L my, I can hold hours.
The only complaint I have is the presence of the separation loop at the back. It would have been better to put it in front for security reasons, or not to put all; but it is essential to install the covers Joey (which I do not need ...).
Risk therefore in the crowd to get off the strap in the back (what a voluntary thief - in Las Ramblas in Barcelona or Paris, for example - use a cutter, but ...) and get wrest his material.
But I found a good parade and a solution to prevent "unclipping" of the strap using 2 small plastic collars cut flush after tightening.
In short for me this strap changes my life photographer, and after over 30 years of practice of photography, I can guarantee that you will find no better system than the Black Rapid principle.
And you know what? I am so captivated by this brand that I also bought me the model "Metro", more discreet, in order to make street photography with my EOS 5D MkII + Pancake 40mm or my 50mm f / 1.2 come (if My banker is ok ...!).
Furthermore it makes me always 2 screws mounted (or almost) on my grips.
Oh yes I forgot. In reading the reviews here and there on these straps, I read that the photographers had their fastening screws unscrew ...
Let me laugh! It really does not take very fûté not to tighten the screws strong enough (mine is souquée) and especially to check the time of clamping force then.
My 5/5 equivalent, you will understand, to a 20/20.
I wish I was the inventor of this revolutionary system.
Note that there are also models specially designed for women (no discomfort in the chest), for sport (whatever the strap under the arm does not provide much ...) and many Accessories including a special screw that can accommodate a fixing loop in a quick release tripod or monopod Manfrotto.
A buy eyes closed (very good investment despite the high price compared to the USA) for any expert or pro photographer.