I've been thinking about something else entirely that hasn't been mentioned here, but I haven't bothered to download the PTR and try it out (default bars make me irritated).
The purpose of 15/30 stacks was originally because we would end up getting more TEB than we do on live with the new mastery, yes? Well, I already find myself getting up to 20 stacks very quickly (around a minute to a minute and a half depending on 4p procs) if Roro doesn't proc for a while. With the cap still at 10/20 stacks and an easy 15-20% extra TEB stacks, doesn't this kind of devalue the entire gameplay surrounding TEB as it approaches even 50% uptime? Perhaps in an overall design point of view it's not a big deal because we only have this much haste/mastery for this end tier of the expansion (and ilvls have been drastically increased WotLK style), but for the moment TEB seems kind of pointless as a mechanic if you're forced to have it up most of the time anyways. Again I haven't tried it, but it seems like the "optimal window" with trinket procs and no movement is something we're going to have to get used to missing because TEB has to be popped so often.
Does anyone on the PTR see this as an issue?