Im at work and can't access the link, but I recall reading that something like 405 haste (all the items available in S4) are equivalent to a 22% increase in haste. With Bloodlust being equivalent to 30% haste. This does not equal 52% spell haste. I recall the gentlemen trying to achieve a lightning bolt cast time uder 1s. It turns out that the bloodlust haste is applied to the new modified haste spell.
ie. 2s Lightning Bolt X 22% haste = 1.56s
If we then apply the Bloodlust haste we get
1.56s Lightnig Bolt (22% haste modified) X 30% haste = 1.092s
Normal Bloodlust Lightning Bolt cast time is equivalent to 1.4s. So we are currently trading some number of spell damage for haste (If anyone can get the exact numbers Ill update the post). .308s Haste seems like a small improvement. If your multiboxing multiple shaman we have two things working against us: This diminishes the amount of benefit we recieve from Bloodlust (which is always up in the arena) and we rarely are in a mode where we are casting bloodlust free lightning bolts.
Here are some things to think about (not stating them as fact, just something we might want to look into):
In the time you can cast 3 lightning bolts you can now almost cast 4. (almost = 25% increase in dmg)
Totem of Wrath will now has an extra opportunity to add damage (+9% crit = 200% dmg 9% of the time = +18% normal dmg).
Arena Bonus Set: 50% uniterruptable. Since your cast time is shorter theres a smaller window to interrupt you. Regardless if the other guy has more or less haste, the attempts they have to interrupt you are less from this bonus. I would expect an increase in damage to be around 11% (50% of the 22% increase) compared to the same non modified casting spell.
Lightning Overload: 20% chance to proc an identical spell taht does 50% damage. Nice bonus aye!
Of course after playing my Shaman for over a month in Full Wellfare epics with the 41/0/20 build I can say any team stupid enough to sit infront of my shaman and go toe to toe DPS loses. Thats my game. Throw in the typical LoS Jockeying Mages and Druids and its all over. None of this matters. Plus I think it takes 1 lightning bolt, 1 Chain Lightning, and an Earth Shock to take any target down. Which is why I think the 4X shaman nuke power works so well in the 5s arena. Dropping an opponent at will is priceless. Once the lightning bolts get going its gg (especially when they cant run away).