I am almost positive the haste cap has been modified to be capped at 500. Being as it is that high it is better to look at minimum delay than the haste cap. Minimum delay to my knowledge has not been modified and is 10. The monk 4.0 has a delay of 19 so anything above 90% is no benefit. That does not mean that your t4 monk clicky is not beneficial. It also increases your hit damage. I am sure you have seen that it is like having innerflame up permanently.
All that being said, sorc, sorc, sorc.
Edit: EQ haste calculator link...
http://gaming.invisibill.net/eq/hastecalc.html