aI think at the end it boils down to personal preference. Both may be right. I personally would prefer R7 if I had to pick, but that doesn't mean R7 soft would not feel better for someone else. Know a guy who plays with T05fx on his BH, and no-one has such BH spin as himself, at least in the town. Tremendous, you'd say how the hell is it possible with that soft thingee. So, don't worry.
Agree. I use Chinese rubber on my forehand. Look, Ma Long uses hard Chinese rubber on his backhand so should I do it too? Not necessarily. I would not in a million years try to use Chinese rubber on my backhand. I don't have the technique and the strength to do that.
I have tried Rakza 7, Rakza 7 soft, Rakza X, Tenergy 05fx, Tenergy 80fx, Tenergy 64 fx, C-1, etc. on my back hand and I ended up settling on G-1 which is harder than C-1 but yet not as bouncy as the Tenergy series. Why G-1? I don't know. It just works better for my backhand. Well, isn't C-1 and Rakza 7 softer? So maybe they will grip the ball better? I don't know. I just feel that G-1 works better.
I think a lot of equipment choice depends on your technique and physique. Unless you try it, you really do not know. I just like the way G-1 feels when I brush and block the ball....
If money is not a big concern for you, why not get two sheets of each R7 and R7 soft to try it out?