#0 - April 20, 2007, 5:55 p.m.
Blizzard Post
The developers have been doing dps testing recently and, while mana efficency may be lower, it is still reasonable with around 18% crit to have decent LB spammability for a period of five minutes.

They are doing more testing in regards to this, but I don't think they see any "brokenesss" of sustainability for Elemental specs.