So, I've been skimming the DPS forums and there are several threads there that talk about using WoD/crafted pieces over dreadwyrm because you get 2.2* extra DPS due to better secondaries.

Now, I am aware that DPS and healing are two very different kettles of fish when it comes to optimising gear, as DPS chain skills and so secondaries on lower ilvl gear can actually be more efficient and generate bigger numbers over the course of a fight.

My general view on my SCH has always been to get as much crit as I can, but always prioritise iLvl cos MND is great, and the return from secondaries seems to drop off substantially as soon as you stop chain casting.
I am not a theorycrafter, so I don't have numbers to back this up, but it is just my experience.

*this is a random number I just made up for the purposes of this post.