Putting the entire meta-forum discussion aside, TEB has been changing so much that I can't remember which build the conclusion that Ascension was still barely better than CB came from or whether that discussion included the 4 piece, which has also received a significant change since it was first revealed.
So starting from square one, we know that the chi-granting portion of Chi Brew is the same even if it's on a charge cooldown now, functionally it is the same except it will have slightly less variance over the duration of a fight. We also know that the TEB granting portion that was added this PTR is worth exactly 4% damage (2 6% stacks that last 15 seconds on a 45 second cooldown) on an infinite timeline, although because it starts off cooldown it is anywhere from a 24% damage increase on a 15 second or shorter fight, approaching the 4% mark as time gets closer to infinite, but probably around 5% for our purposes. Prior to the T16 4p nerf those 2 stacks would account for half a chi, but now only accounts for one fifth of a chi, putting CB at 2.2 chi per 45 seconds, or 44 energy, which is oddly very very close to 1 energy per second, but I'll call it 1.25 based on the same estimate as The TEB stacks (from 4% minimum to 5% estimate).
Ascension is worth 1.25 energy per second when base generation is 8.333 energy per second, which we clearly start off with, so even with the 4 piece Chi Brew does not even come close (roughly 30% less with current haste values [highly varies depending on what your haste is like]) in terms of pure resource generation, but what about that TEB? Honestly, I don't know.
Anyone that can figure out whether 5% damage is better or worse than ~0.7 energy per second deserves a cookie, have at it.
Oh, also no clue if the TEB stacks benefit from mastery or not, does anyone know?