With AoE healing in mind and the haste buff in deep holy talent tree for +10% from judgement, I reckon with a simple alteration of this base holydin mechanic, the holydin could pull off AoE healing with coordination naturally.
Simple change, with HS[Holy Shock] being the main healing use (I bet come wotlk and its focus), is on every HS cast to have a 33/66/100% chance to remove Flash of Light off the global cooldown for 4 seconds.
Add into the equation haste buff from judgement and the vast amount of haste stat on the tier7 gear and other healing items, one can vastly reduce the casting time of FoL to such that one could fire off a few of them on many raiders affectively healing many in a matter of moments. Without that harmful GCD affecting the cast it would prove immense and not having to rework or add yet another spell to holydins.
Wouldn't this prove very useful in both PvE and PvP environments, making diving deep into holy a valid course of action? Nevermind it complementing the whole holy tree as a whole but with special mention to the skills Sacred Shield and Beacon of Light.
Of course replacing Lights Grace current mechanic with the above description.
Thanks for reading.