In 25mans holy is a joke.
But in 10mans I would've liked going holy on heroic thok, since blanket renewing the raid would've given me 350k healing per 1.0 GCD without procs(if 0 overheal) compared to blanket shielding's 240k.
Na just kidding, my 45% mastery doesn't actually work on renew, so with 0 overhealing a renew would only heal 235k overall, useless, I'd rather just go disc since disc has the bonus effect of doing 70k dps and effortless smart healing during the kite phase.
So, why the hell does renew not work with mastery while everything else does? If it was hard to program it with echo of light then couldn't mastery grant a flat % bonus to renew?