People fail to understand how little of a difference a BiS determination setup vs a BiS spell speed setup really makes. From another thread I posted in...

For a determination BiS vs a spell speed BiS setup, the differences are:

Det BiS: +73 determination ( approx +30hp / cure, approx +49hp cure 2 )
SS BiS: +71ss (-0.07 seconds per 2.5s GCD ), +25 piety
Minor differences all around. While -0.07s to the GCD is minor (but also benefits from 25 more piety), I wouldn't exactly call an extra 30hp cure a big deal either.