OP didn't say he wants something similar feeling, did he? He said he wants a faster setup with a tacky topsheet.
His current rubber is likely too soft to begin with; that's why he is changing. That's a 42deg~ Shore O rubber.
My current setup is around 53/48 Shore O, and I could go a bit higher on the backhand hardness. I'm not some super player; higher beginner or lower intermediate is probably accurate. Going softer just increases my injury risk, like how using Europe DF on the backhand gave me shoulder pain due to how slow it is and how large of a swing it requires, despite topsheet tensioning.
I can do slow, spinny shots all the same, despite the Young's modulus differing about +90% on the Moon Speed I'm using right now vs the Europe DF.
There's a good chance OP is similar or better skill to me judging by the descriptions; so what's the problem?
EDIT: Also, FX-P is 40.1 +-1 and FX-S is 42 +-1 Shore O. The sponges are effectively the same hardness; both are super soft. IIRC they differ in topsheet and pip geometry.