Yeah, the procs are just so strong, I can see them being better than a regular meta even with reduced rates, but it really depends on the numbers.
I have both metas now (caster spellhaste and healer no-mana-cost procs) so maybe I'll mess around with it and try to figure out what their actual proc rates are for PvP on live (we all know that we can't trust blizzards random one-off comments during beta about what will happen on live, and we need to actually measure the real-world numbers to get any accurate info).
Problem is just that I have the metas in PvE gear, so I'd either have to test in PvE helms (and likely the proc rates are only adjusted in RBGs and arenas, not regular BGs or outdoor pvp/duels, so I'd have to use a PvE helm in rated matches), or I have to drop ~2500g (the price of 5x primal diamonds) per meta just to test, plus the cost of replacing my old meta if it sucks. Was hoping someone else had some numbers so I could avoid taking that risk.
If I do it, I'll probably just screw around in 2s or something, but it still takes a lot of testing to figure out an accurate proc rate with any degree of confidence.
EDIT: Just realized that the legendary metas require an ilvl 502+ item to equip, so you can't even put them in any of the PvP gear. They would have to be good enough that you'd want to use a PvE helm, which seems really unlikely (and you'd probably want a 541 heroic thunderforged helm if you did it). However, with the upcoming removal of resil from gear, there is still some possibility of finding a way to use the legendary metas in pvp. It's unclear how the downscaling of ilvls on gear in pvp will interact with the i502 legendary metagem requirement.
Edited by Lilyi, 24 April 2013 - 10:37 PM.