How shall I spend my Emblems of Frost?

As a casual player, the only times I see the inside of a raid instance are when I get lost or asked to fill-in for a dropped player. So, my chances of having high-end warlock attire are limited to those few drops in Heroic 5-man instances, seldom raiding experiences, and what I can buy.

Bring on the heroics. With 3.3, if you are ambitious and log on for about 1 hour each day, you can net 14 frost emblems by doing the random daily dungeon. If you time it well, you can add the regular (weekly) raid along and net 5 more emblems.

Last month, I broke down and purchased the Tier-10 shoulders for 60 emblems. This was the best upgrade for me at the time. Now, I am back up to 40 and want to start planning for the next big purchase. At this time, I am considering replacing my chest piece. Already broke the Tier-9 4-piece bonus when I replaced the helm, then shoulders.

Here is my concerns:

1. There are two chest pieces available for 95 Frost.
   
2. Meteor Chaser's Raiment and the Tier10 Dark Coven Robe
   
3. The Raiment is the stronger piece, but
   
4. The Dark Coven is needed to buy the next upgrade the Sanctified Dark Coven Robe (which is an even better upgrade).
   
5. In addition to the robe, I need a Conqueror's mark, which you only get from raid drops.
   
6. I share the same mark, with 2 other classes.
   

So, considering that I seldom get into raids, should I go for the one-time better MC Raiment? or shall I hold out hope that I might get into some ICC25 for the Santified marks to drop??