The general word of mouth is that Affliction is supposed to be stronger on a single target than Demonology, but at any time when I try Demonology (I'm Affliction mainspec) I do quite a bit more DPS (~100k vs ~135k on a Dummy, for whatever it's worth).
Now, I wouldn't mention this normally, as I always regarded Affliction as a spec that shines when you can DoT multiple targets, but I hear so much about Affliction being great single target that I wonder what I'm missing.
For the record, I know about the basic Affliction rotation - keep DoTs up, game your procs into your DoTs along with your CDs, Haunt when you've got strong DoTs up, etc. - I can't see what I could be doing wrong in single target, so what's the deal?
i would stick with demo, till u can get the 9778 haste rating, and Khoorm is right afflic is very gear dependant, and until u get around 530 ilvl i wouldnt go afflic, unless you really want to, or are actually going into SoO, cause afflic is the best spec for that place by far.
I think you're missing something with procs / not haunting enough. 100k dps is low even for 500 ilvl. 135k for your ilvl as demo is prob about on point, I think you just know how to play demo but are lacking with aff.