So just to throw some conclusions from my theorycrafting out there.

If all he above is assumed to be true one would see an added bonus to DPS of :

25% (fom an extra LB) + 4.5% (Extra Benefit of ToW on the extra LB) + 11% (from being interrupted less) + 10% (from Lightning Overload Proc) = 50.5% increase

This is assuming the same spell damage and at least 4 lightning bolts casted under Bloodlust.

So according to this +600 Dmg would be equivalent to +900 Dmg with zero haste under Bloodlust. The ToW bonus is small, +4% is still a nice bonus on top of the haste though...

I'm at work again so I would be interested if anyone could link the +dmg loss for + haste increase. I dont think the numbers come anywhere near where they should to be an equal trade. This leads me to believe that the utility of casting faster must have a greater benefit in use than just straight DPS. The typical MB build is about Focus Fire Power (FFP) and atm I dont think haste fits into the picture. Its a lot of work for the novelty of having Haste stuff...but Im thinking about it