Rxton 9 for me feels too hard, the 40.5 deg is hard not that fast, tho in short game is was very good, i think probably the best rubber I ever tried, but the arc was very flat. Granted my opponent hated it, said it's extremely quirky rubber.
Rxton 7 has great speed, good contact length, the topsheet material is the same as Rxton 9 and the sponge is probably the same too, but overal feels so much more fast and lively. It's like comparing D05 and D09c, I mean the difference in topsheet. I'm sure the pimple structure is different.
I think Rxton 7 is a lot more usable as it is than Rxton 9.