I've had 3 sessions with them now. They feel a little harder than the equivalent R version, topsheet feels a little tighter, and a touch slower but not hugely.
Comparing R48 and C48, or the 53 versions, I think there are 2 main features - better spin on brushy contacts, and a feeling of the ball "holding up" on counters. It's impossible for me to say if this grabby feeling is just the tack or if the pip structure is contributing - how would a person know for sure?
With the tack being so slight, the speed stays relatively high in comparison with Rakza Z, which helps the flat game.
I really like C48 and it's going on the BH side. It has the best mix of properties I've seen recently on that wing - very high grip for flips, good mid/high gear speed for punch / flat kill shots, not overly bouncy for touch play. No real weaknesses, good performance across the board, but predictable and stable when you're doing the basics. If you twisted my arm to pick fault, maybe it's a little spin sensitive on very passive shots. But it's a rubber for active play, not for standing still and passive blocking.
I find C53 easier to use in comparison to R53, but it's still hard and demanding. It feels amazing in drills, when you know where the ball is going and you can get a full stroke in. In free play I find it easier to get along with than R53 when out of position, but it still needs big effort to extract top performance from it, and low effort shots give a weak output. It might react well to a little bit of booster, just to soften the sponge up a bit, but you could consider a C48 in ultramax if that's not too soft for your taste. Or stop being so lazy, move your feet, and play a proper shot as sensible people would say. Sounds like too much effort to me, so I'll give C48 a go on both sides.
Durability - no idea, too early to say, but they look good after 8 hours.