It has been buffed recently, and is now very strong, particularly if you have generally valued regen high in progression where mana is constrained. You can just assume it will give ~40K per minute, sometimes more, sometimes less (both proc and casts will vary), and will have value on some fights.
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The correct version is here:
http://www.wowdb.com/items/128710-da...s?bonusIDs=669
At 1150 average, it breaks away from the Alchemy trinket at ~2:45 fights at a conservative 30 casts per minute; at 45 casts it breaks away at ~1:50 or so. So it has become our best "regen trinket", the TP versus regen arguments aside.
Calculating the value of a medium/large amount of static versatility and an huge intellect proc; versus a large static amount of intellect, is trickier.