Looking for advice on the Holy Archangel spec.

[Negash]

Priests of Paragon, I need some advice on when to build evangelism and when to activate archangel in 25 man heroics.

I switched to this spec http://www.wowhead.com/talent#bcroZfurMR0rkfzob:aVod0qzV0 with the release of 4.0.6. (I know that Discipline is currently overpowered, but let's assume it gets rebalanced.)
In Chimaeron I had no trouble, but in Magmaw, the only chance I had was on the Impale - is that normal, or should I have more opportunities? The problem I often find, is that while smiting I do no healing, potentially costing a raid member's life.
Are there any fights where there is zero opportunity to build up to archangel? Maybe I should have more haste to grab the smallest windows of opportunity (currently at 12.7% raid buffed) or is that the wrong thinking?
One last question; will evangelism stacking for archangel reduce my overall healing done, but boost my spike healing where it counts? Or does that burst make up for any total healing lost by smite?

Thank you for any help.

[Jhazrun]

I've grown more fond of Archangel than most, but even trying to cram it wherever possible helps Holy little.
Rest safely assured that there's no true worth to be found without pre-patch Tide to fuel it (excepting Sintharia and [Shard of Woe]).