Honestly people int his game min/max a little OD.
I remember trying to convince the entire WoW community that frost (mage) was fine back in firelands, esp with 4 pc. It was ~2-4k dps behind arcane and fire. You know what everyone said?
"Why are you gimping yourself?"
"lol, frost sucks. Go pvp nub."
"Frost is so far behind fire and arcane"
blah blah...
ON PAPER yes, but anything between 20 and 45k is player skill imo. If you're better with the spec, play it. WoW's community has always had this silly hive mentality when it comes to dps specs. It doesnt matter much anymore, not for a long time now anyway. This is not bc lol
/rant
It depends on the class/spec. Some specs display a higher delta between players dps, and others are just less rewarding when perfectly executed. I think demo is one of those specs that require not only excellent gear, but excellent player performance and practice to get timings right during combat as well.