On a occasion got myself a red R50 on ultramax sponge... didn't expect much from it, because recently bought R47 with 2.0 sponge and wasn't impressed with it's performance compared to tenergy 05 max rubber that I use on both sides of a blade (tried it on Apolonia ZLC blade... on BH it was "so-so", on FH not bad, but 05 is much better), I just wanted to try new blade that I bought (Innerforce ZLC)... but, to my surprice, R50 ultramax was fantastic on FH, especially when you make powerful topspin, I was quite dumpfolded when I realise that the more powerful topspin is the more control you get (with 05 for me it's quite an opposite), also the powerful topspis has quite low through angle, but still have a lot of rotation and (as I already sayd) a loooot of control, so it's quite hard for the opponent... the thing I didn't like in R47 2.0, the "cushion" feeling of the sponge, in R50 ultramax on FH is a great thing for short play and block, but, as I sayd, topspin is great thanks to hard and thick sponge... the are still cons though, when you try play relatitely "soft" and slow topspins control is lacking (I think the "cushion" feeling of the sponge is a main reason), so IMO if you attack with this rubber it needs to be done with some power, "soft" attack is not for this rubber, and for my lousy play it means that this rubber is not for my BH, which doesn't have much power, so on BH I prefer Tenergy 05 which compensates my lack of power with bouncy sponge...
So my choice for now is R50 ultramax on FH and Tenergy 05 on BH... but it's a choice for Innerforce ZLC blade, still haven't tried R50 with Apolonia ZLC blade, hope it will be as great as on Innerforce... also, currently Innerforce ZLC with red R50 ultramax on one side and Tenergy 05 1.9 on the other is weight quite much and have quite noticeable overweight to side of the racket with rubbers, and I like it, it helps me to accelerate wrist on the topspin in the moment before racket contact the ball which probably give additional rotation on power to the ball, so maybe some part of my WOW effect of R50 is actually due to that...