Heirloom questionFollow

Why would you want to level as destro?

Check out this comment on leveling.

I would suggest looking at the demo or aff trees for leveling purposes.

In regards to the trinkets, spellpower will always benefit you more than haste, except perhaps in some extreme gearing/encounter scenarios that you won't be contending with as you level. So yes, while probably the absolute best situation is to get 2 Discerning Eye of the Beast trinkets, I don't think it is that much of a make-or-break decision on which to use as you level your lock. After all, the general lack of trinkets altogether means most characters at lower levels have no trinkets or (usually) inferior ones from quest rewards. Based on the equip effect of each after you kill mobs, it might be useful to have one of each, thus you restore both health and mana from each kill and get both a spellpower and haste benefit. You'll kill mobs quicker and be able to utilize Life Tap better.

Spell power will always be better than haste, however the life/mana back option might make it a little different.

Leveling as Destruction is fine. We can go back and forth on which spec is the most efficient and nail the positives and negatives but the fact is that all three specs are very efficient when it comes to leveling. Affliction lets you drain tank multiple mobs at a time and end up full health/full mana, Demonology lets your pet tank multiple mobs and you end up with full health and mana, and Destruction lets you kill things before they even touch you and drinking for mana slows down the speed to where the others are. You can level quick with either tree, each with it's positives and negatives, there no longer is one spec that's best.

I didn't know this (Looks like I need another one). Awesome.

However, are the "broke"? I've been leveling a Lock through PvP/LFG and at the end of a fight/kill I see no mana returned.
Maybe I'm just looking a split sec to late...