I bought RS-7. While I love it I don't like the extra buckle compared to RS-4.
While it seems to be firm, I don't like the idea of having extra plastic point of failure on my camera strap. Also I think it could be easier for thieves to steal your gear just by opening that buckle on RS-7 and running away. I prefer original RS-4 design.
I think this buckle is more a big design compromise as Black Rapid believe they can sell us more accessory pockets, etc. if they have open design.
Should I need a new strap, I would get original RS-4 instead.