Turns out skill speed doesn't change the impact of removing Phlebotomize one way or another significantly.

Best 3 minute sequence I can come up with for no Phlebotomize is 1529 dps versus using Phlebotomize at 1549 dps. Subtract 5 from the Disembowel effect for BRD, and you're looking at losing 25 raid DPS in exchange for extra TP, I guess. But, TP is not really a problem in the current raid tier. There's so many breaks that if you use Invigorate at correct timings, you'll probably never run out of TP, even without a NIN.

I suppose if you're TP starved for a significant amount of time then it's worth it, but by my estimation you'd probably have to be TP starved for at least 20 full seconds during the fight. I would say you just need better TP management then.

This is, however, significantly better for AS2, due to the extra Geirskogul/min hitting multiple targets. If each Geirskogul hits just 2 targets, it's superior DPS on top of saving TP.

Keep in mind that the reduction of 25 dps would make dps checks ever slightly harder.

In conclusion, any raid that you can consistently hit 2 or more targets with Geirskogul would benefit from dropping Phlebotomize. Otherwise, TP management is probably the answer.