Didn't have a single gold trait until today(went utility route 'up then turn right' to Mass Hysteria). Been pulling 80-90k at the same ilvl and now at 814 pulling low 100's/mid 100's depending on the fight. I think moreso than pretty much any spec out there, there's a high room for failure if you do parts of the rotation even slightly wrong. I'm not saying people need to 'L2P NUB', but sometimes there's one part of the many things shadow manages that can get forgotten in the heat of combat. It's definitely pretty layered with nuance depending on your talent choices. Especially if you pick some of the non-standard things and misuse them even a little wrong, like not using Shadow Crash on single target or overshooting 70 insanity(with Legacy of the Void) by a large margin with a Shadow Word Death(with Reaper of Souls) when you could have mind flayed for a fraction of a cast to tick over saving the SW charge.
Edit: Looking at simcraft, I noticed something interesting. Surrender to Madness in particular seems to be the pinnacle of 'room for error' that I've ever seen on dps rankings. It's 7th on the charts, pretty high up there....but the room for error, the 'minimum' of that, is lower than the lowest on the chart by 40k(the biggest margin between any spec in anything). The range between the minimum and the maximum on StM is as big as half of the entire damage is does on that ranking. Most others are barely a quarter if that. Just food for thought about the 'room for error', and how even the tiniest of mistakes from competent players can hurt your dps.