Butterfly R40+ vs. S40+

Which is better? S is the new ABS, and R is the latest ball and poly, so what was wrong with the S? ABS is supposed to be more durable, but my guess is that it is less bouncy and not as bright colored as poly.

Nevermind, since it seems the R40 are the only ones available.

I wonder what was wrong with the S40 ABS balls, and why I can't find any details about why it isn't available. Something smells scandalous! This reeks of a cover up! How is it not possible to find the answer to such simple questions on the Internet?

Some time ago there was a factory in Germany which manufactured the balls for Butterfly exclusively. First G40+, then S40+. Those were OK in terms of hardness, roundness and overall quality, but they were hard to spin due to the plastic used. So recently Butterfly switched back to chinese manufacturer for R40+. That's what guys at TT11 said in this video (in Russian).
I think I heard somewhere that R40+ are produced by DHS. If so they should be the same as DJ40+, I guess.

First Butterfly plastic balls were terrible. Producing strange sound on each shot like it's broken. Almost no spin.