The heal over time effect from casting Flash of Light on a target with Sacred Shield is no longer part of any tooltip, nor has it been for a few builds now. At this point, it's safe to assume that the Flash of Light hot isn't making it in Cataclysm.
And the "datamined" Holy Shock heal over time effect is our T8 2pc bonus. There is no indication that Holy Shock is getting a HoT attached to it. In this case, it's safe to assume that Holy Shock is *NOT* getting a HoT attached to it. If it does, the whole situation can be figured out *AFTER* it's been implemented.
As far as Tower of Radiance goes, the ability is fairly underwhelming right now due to the following facts:
1) Word of Glory cast with 3 stacks of Holy Power heals for about 20% less than Holy Shock while also having 12% less chance to crit and not proc'ing Infusion of Light (which is currently bugged and still working off of Flash instead of HL) making it the second weakest single target heal we have behind Holy Light
2) Holy Light spam on non-Beacon targets is currently our bread and butter in terms of throughput and sustainability
3) There is no reason to directly heal the Beacon target (a tank) unless the tank is taking more damage than you can heal by spamming HL on the party or if the party is taking no damage
4) If you have to spam the tank because the tank damage is otherwise too high, Word of Glory will only serve as a mana saver, not a throughput tool
5) If you have the time to use Word of Glory to heal your Beacon target, then no one is really taking that much damage anyways or you're extremely strained for mana
All things considered, you only get a small amount of mana saved if you're actively spamming your target. In 5 and 10 man scenarios, this would be potentially worth the 3 points. But I can't see too many scenarios for a hard mode encounter where there is a prolonged absence of raid damage and extremely high tank damage going on, meaning the talent points would likely only be picked up for specific encounters. In other words:
WoW Talent Calculator - Sigrie or
WoW Talent Calculator - Sigrie.
Light of Dawn doesn't transfer healing done to the Beacon target. A Paladin who reached lvl83 could easily confirm the same for Healing Hands.