Demo is easily fine for Spine HC.
I don't see how you can count defensive/movement abilities as beneficial towards a fun dps rotation. Also, I think you're underestimating how much a loss of just a few moves can make. For instance, the removal of Shadowflame means that instead of using a different spell every 12 seconds, we can continue spamming Shadow Bolt, yay.
Also, in Metamorphosis our rotation is reduced to like, 1 or 2 moves or something stupid.