SMN BIS 2.3

[Ambiguous]

Well doing a quick math check based on all the best gear that have spell speed and with 486 accuracy, any fights where you can use Ifrit, full spell speed (511 with food) might actually be good.
I.e. lower Crit, but more attacks from Ifrit to activate Enhanced. So ideally you stay close to 2.24GCD 10% faster casts vs the 3% damage you lose from BiS.

I'm a bit confused why you believe increased Spell Speed will lead to Ifrit-Egi doing more attacks, considering this post states otherwise.