Without Art of War procs most rets have Exorcism on ~12sec CD now anyways so the 6% holy damage should have ~50% ish uptime, this depends on offset itemization for next tier ofc. No haste, no love.
4set is going to be fucking annoying, 2-4 holy power you'd want to use crusader strike then templars verdict asap if the shit proc. Is it going to be more than 30% more damage from templars verdict anyways?