If the grip is only bad thing, try grip tape. My favorite is butterfly, it adds about 5g.
I also think Nittaku (Japanese blades in general) has mostly too skinny handles. Their best blades are (I think) made by soulspin with a spruce top. I love the basaltec inner, but this one is really expensive.
The Darker 7P-2A is on the stiffer side so is the septear I think.
You mentioned S-CZ, it is made by soul spin and with a spruce top. That’s the blade I am playing with right now. I love it, it has the right amount of everything and it’s not too heavy with grip tape.
The Hino blade 7.22 I find a little too stiff as well due to the inner + outer + 7 layers. So for me it’s not the greatest looper.
Right now Nittaku S-CZ would be my recommendation. It’s an outer carbon layer but it doesn’t make it too fast. Thickness around 6 mm.
Cheers
L-zr