What are you doing during DP if you aren't dot weaving? (which is what I assume is putting up dots during DP & mind flaying). Or do you just mind flay with insanity and not worry about the other dots.
Personally I've just been doing normal old dots + mind flay with mind blast being my #1 priority spell after sw:death. Pretty much always right at the same dps or above the other SP I raid with that's doing the nuke spec. I just like the feel of playing dots & flay I guess.
You mind flay with insanity during DP for pure CoP. Sometimes if there's a lot of adds that aren't all going to die in 10 seconds I'll multidot and weave on the boss (or just skip mind spike altogether, and just multidot and save dp and insanity for the boss).
Dots and flay are definitely fun, and is pretty ground in my memory muscle after doing it for so many years. I still think it's dumb from like a...lore perspective or something that our mastery, which was originally designed to make each class better at their main thing, goes against what the shadow priest's main thing has been for many years (dotting). I get why the previous mastery didn't really work in WoD, but it not enhancing dots still feels wrong. Then add in the CoP talent, and now Shadow itself is like 3 sub classes at 100, heh.
If I was in a consistent raid group or doing anything challenging I'd probably pay more attention to what does more dps for me personally, but it's all probably a wash and depends much more on someone's ability to execute perfectly while paying attention to fight mechanics. The other guy could just be crappy at it. Or have lesser gear. Or missing enchants. Or the sims once again aren't very relatable to real world fights. The sims show CoP really killing it, but I think they're just based on patchwerk fights. I believe it should still mean that's the highest theoretical dps, but even with CoP, you're supposed to be dotting adds I believe. Not worth it in heroics though.
Secondary stats for shadow are kinda all over the place. CoP, Dot Weaving, CoP Lite, plus the other two level 100 talents, all have different stat weights, but again it's a case of "sims vs real world". Even in the sims, compared to a point of intellect, the range for them all is .45 to .55. If you wanted to be crazy you'd have to have different gear for every fight depending on what kind've adds there were, plus changing out talents, to really "maximize" it all. But that shit just doesn't really matter unless you're doing Mythic progression or something, in my experience.