If I may offer a piece of advice in general, you should try (as should all Holy Paladins) the Glyph of Divine Plea. The 4-5 second cast time (mine is 4.4 with no haste stacking) is so much better than 12 seconds of 50% reduced healing, therefore burning through more mana during a panic, seeing how it's so hard to time 12 seconds where you can stand around twiddling your thumbs.
Ahem. Nine seconds. ;)
I prefer being without it in most cases. While it is technically nine seconds, 3 seconds are consumed casting it and a Holy Shock that will come off cooldown during the duration (yes, the Holy Shock will be at half healing, but the Holy Power gain will totally be at full strength, so only a marginal loss!). And one can also precast a solid heal towards the end, shaving off another second or so. The few seconds left over I use to scope out the raid, get a good overview of upcoming DBM markers, use utility specials, find out where I've hidden my mana potion on my hotbar just in case, and in general just take a breather.
And move, of course. Sweet potatoes, I love being able to recover mana and move at the same time. On the other hand, there are definitely fights, especially now that my guild is starting to 2-heal a lot more, where I could be losing a Divine Plea as I twiddle my thumbs with it off-cooldown until a safe time to use it pops up. And it's not like I really *use* that Flash of Light glyph.
On topic, yeppers, Spirit > Mastery > Crit > Haste, so long as haste doesn't drop off too far, which I don't see happening from the way gear is itemized.