But I also find that if you read a review from a sensitive player, their impression of the throw or arc, and speed will give a pretty good impression of what to expect.
I've also seen the butterfly tenergy video, and what they say about 05, 80, 64 at least is true from experience.
Yes, I completely agree on both counts, at least for speed and spin and throw, especially from some of the reviewers here who I know have tried a lot of different things and who I know have a history of liking the same kinds of rubbers that I do. In time you kind of figure out who some of these people are. Patrick, Yogi Bear, Andy Smith, NL, are a few of the people here who's reviews have been spot on when I tried the rubbers myself. Other people too. (There is still nothing like trying stuff yourself, though).
The Tenergy series is really interesting because the only thing different between 05, 25, 64, and 80 is the structure of the pips on the inner surface. The effects are quite complex, and depend on the diameter and shape of the pips. I am sure Butterfly has all sorts of high-speed video testing they do but keep pretty secret (since after all, the idea of measuring these properties under really controlled conditions is hardly new).
The rubber I am using now, Karis M, has gone about as close as you can go to
eliminating the pips on the inner surface of the top sheet, while still being legal according to ITTF. I have to say, it makes the rubber a lot easier to figure out from a player's perspective. The topsheet is also really thin and soft. The idea is to make it really work in unison with the sponge. It reduces some of the high end performance but makes it really predictable, which I am liking.