I was forced to go destro by the drain soul nerf. But I feel that destro is getting alot like how affliction is, which is a good thing imo.
the improved soul fire buff will rarely be up in a raid situation as most fights you use hero/lust at the start and it doesn't stack, but anywhere you can exploit the proc (slimes on rotface for example) I'd lean towards not casting chaos bolt, with my current gear, incinerate is critting nearly 1k harder than chaos bolt crits.
As for dethdealer above, I'd definitely drop the mastery to reach the sweet spot of 1406 haste, because not only does it increase the conflag damage from the extra immolate tic, it will boost all of your casts, and saying you're at 1297 haste at the moment, the extra 110 haste is a big deal in my opinion
I managed to get the haste sweet spot whilst getting good mastery (18% bonus fire damage), and also maintaining just under 30% crit, and i'm really pleased with how its performing for me.
My armory