Glacial Augment/Unsealed Spellbook on enchanters?

I've been in between both Unsealed Spellbook and glacial augment. I've been really enjoying Unsealed for its 25 CDR, stacked with lucidity boots and the 5% cdr from inspiration, not to mention surprise teleports from Janna which are gamebreaking. It also allows you to start with ignite in lane to give you snowball potential, then swapping to exhaust for teamfights later.

But supports can get 65% item CDR with ingenious hunter, inspiration keystone, and ruby sightstone. This lets you almost spam FQC, GLP, Randuin, and RG, which cause huge long lasting slow fields with Glacial Augment. GLP in particular is very impactful with this keystone.

I understand that this means you lose out on Arc Comet's/Aery damage, but the utility to be gained from this rune selection is staggering, and the massive CDR potential on both abilities and items makes the game almost feel like URF. I've found it to have far more use in teamfights than the very slight damage increase from the offensive keystones.