Why would you even consider Fleet Shadowspirit? We get 15% from ancestral swiftness and that doesn't stack with anything so basically you are comparing 54 mastery vs 21 agility and 3% additional damage on crits vs 54 crit and 3% additional damage on crits. Guess which one of those is the worst option? Hint, it's not the 21 agi one.

Blue post today shows that Unleash Windfury was further buffed from 40 to 125%.

MMO was wrong about the 40% applying to the direct damage, it was a buff to the passive effect doubling it's strength. The direct damage was 50% of weapon damage up to that point (the tooltip was just bugged) and with that build it had gone up to 125%. That latest bit is more about just finally getting the tooltip corrected.

While a buff to the Unleashed Wind portion of Unleashed Elements was totally necessary, this buff seems to essentially amount to a slightly harder hitting half of a 15sec CD ability and nothing more. With a 15 second CD, and a limit on the haste portion to 6 swings maximum, in a PvE situation, a buff to the haste % doesn't seem to matter (the charges would have been used fully anyways). In PvP, it could be helpful for some burst where the connection to the target is short lived.

Another way of saying this is that the faster you get those six swings in, the faster you get back to your normal swing timer which can net you an extra swing or two in the span of the fifteen second cooldown. As long as the duration of the buff in time exceeds the amount of time of six hasted melee swings, buffing the haste bonus of the Unleash Elements affect is going to be a DPS increase. When you consider how hard we're hitting (World of Logs - Real Time Raid Analysis), an extra hit or two every 15 seconds is pretty huge when it crits.

Edit: After perusing Premonitions logs I'm a bit unsure about something. The raid's DPS was roughly double what it was in earlier days. Is this a fight mechanic for which there is no listed buff or debuff or is it because of new gear (they all have new names > epic premades).

Appears to be the Halfus-Heroic encounter which was recently hotfixed. The dmg here was done with a 250% damage debuff on Halfus himself.

Unreported so far, but the tooltip for Stormstrike now reads "Instantly strike an enemy with both weapons, dealing 137% weapon damage and granting you an additional 25% chance to critically strike that enemy with your Lightning Bolt, Chain Lightning, Lightning Shield and Earth Shock spells for 15 sec."

That is it was changed from 125% damage, 181% with Focused Strikes to 137% and 193% with Focused Strikes. It should read 199% in game, so this is either a bugged tooltip or a bug in their bonus damage calculations.

Edit: Beta Realm tooltips are reflecting real time changes to glyphs and set bonuses.

Just to clarify, the scaling issue was simply real time tooltip changes based on glyphs, talents and set bonuses.

After pounding away on the test dummies for a while, Caster/Melee combos are clearly starting to come in ahead of Melee/Melee combination's with enough mastery rating. Fortunately, Ghostcrawler posted a small update about the issue:

Well, I can't add to the discussion, because it is happening in the US boards again, instead of the Beta boards.
But I see all your solutions except one simple one: How about switching Lava Lash to the main-hand? It already feels wrong that our strongest strike comes from our off-hand and as you can't equip caster weapons in your off-hand, it would solve that problem once and for all.

What about flametongue if lava lash was a mainhand attack? Simplest is really to just to make physical damage matter more, how they accomplish that though is the reason for all the debate.

There is a easy and simple solution to the 2h problem, remove our abilitiy to wear them! It is a more or less useless relic of old times. Currently no sane Shaman uses a 2h melee weapon. The only use of the skill is to show off your Sulfuras in the cities.