Preface: http://www.wowinsider.com/2008/02/27/ptr-notes-shaman-buffs-life-tap-cha...
After reading that, I'm vindicated. Here's why:
Every single Enhancement shaman makes fun of me for NOT putting windfury on both of my weapons. Then they make fun for me having such a fast off hand. Its true, having two slow 1h weapons with windfury blows my DPS out of the water in most cases.
However, I lose the ability to diversify against different targets. I use Rockbiter against soft targets, as it increases melee DPS. Frostbrand when defending or stopping runners, proc to slow movement by 50%. Flametongue against high AC classes as its damage is magical. Sure, I don't put out as much DPS in the form of a burst, but I feel like it allows for better control over my opponents.
I've always run with 'off-specs', I've always worn them as badges, too. I hate having to defend that against every person that spends too much time theorycrafting on Elitist Jerks. I basically just tell people that I know they are 1337 with thier DPS. I then return the most flags in WSG, or defend the most nodes in AB.
In terms of a faster vs. slower weapon (with out enchants or other improvements); I'd still prefer the faster one in my off hand simply because it has a higher chance to knock back spell casting. Sure, the slower one crits a ton higher, but how much does that help me when I'm CC'd or the target gets off a ton of heals?
So, how am I vindicated? Flametongue weapon will now add a stacking healing debuff on its targets. That means, I get a Mortal Strike / Aimed Shot / Wound Poison ability!!! Since it's a proc, the faster the weapon, the more chance I have to apply the affect.
Of course, this is only on the test realm....

