I put enough Skill Speed on in Titan EX for 2.4 GCD on MNK & DRG because of all the dodging. I generally stack Det/Crit on DRG MNK for most other content.

I don't have my BLM up too high (iL78) but I tend to stack Crit/Spell Speed where I can until I have better gear.

I do think your Skill Speed should increase the rate at which you regenerate TP when TP is <400.