Finally i can contribute with something i know for good.
Ive been playing with rakza line for 6 months 30+hours per week.
First thing to know is : where Rakza X is going?
I have too a combo with Rakza 9 BH Rakza 7 FH and it works beautifully.
Why you want to change Rakza 7? Is it worn? Too bouncy or high throw? If yes, then sure, go for it!
It has same degrees as Rakza 9 i think but with a much more compact, hard topsheet. It doesnt come to life so easily as Rakza 9, some may find this really bad and much more as FH.
Rakza X best performance for me was on 5ply springy blades with high dwell, to have that inital kick that it lacks. I much prefered it as BH due its deadness shortgame and viciousness when looping or 3rd ball opening.
Its play characteristics is more comparable to Rakza 7. A hard, spin based mid distance looping rubber. Minus bouncyness and a bit lower throw.
If you are cpen, then just go for Rakza 9, the best i played so far with that setup.
If shakehand and will replace BH, rakza X. Or if you go ham every forehand shot and have a nice footwork, rakza x too, though rakza 9/7 plays easier in that manner.
Hope i helped you. Feel free to ask more.
Thoughful,
Raul Pacheco.