Voltan

I am 99.9% sure the best rotation is LB,LB,LB,CL - Rinse and repeat. I will back this up with some evidence once I have the time (at work at the moment and just about to go on lunch). I myself have tried all possible rotations and found this one to be the best if you have the mana to see it through (its sick mps usage - however I have pretty good gear, 41% crit, and always get a a shadow priest and BoW).

The Rotations I am going to provide maths for are:

LB,LB,LB,CL
LB,LB,LB,CL with FS once every 12 seconds.
LB Spam - Purely for the point of comparison, from experience I've noticed the dmg difference between avg LB, and Avg CL is VERY slight - ~30ish dmg, obviously dependant on +spelldmg, the more you have the closer the gap (?) - Have yet to do any maths for proof.

Watch this space.

Ok, just to edit. Havent had a chance to look through this, still thinking about how to fit them into comfortable rotations without losing .5 of a second every now and then. I'm almost certain now FS is not worth using for a multiple of factors: - 11% less crit, cant proc LO, Short Range, More mana, Losing .5 - 1sec of FS uptime as well with standard spell rotation.