After reviewing the Loot Table for Ruby Sanctum, there were three possible upgrades present.
Let us assume, that a given Moonkin has the full Ilvl 277 BiS List (/drool)
(since we are assuming full Ilvl277 gear, let us assume we are only interested in Ilvl284 Ruby Sanctum Drops)
The three items from Ruby Sanctum that catch your eye:
Cloak: Cloak of Burning Dusk
Bracers: Bracers of Fiery Night
Trinket: Charred Twilight Scale
There is no issue upgrading Frostbinder's Cloak to Cloak of Burning Dusk - Straight Upgrade.
The harder questions are:
1) What trinket could/would possibly be replaced by CTS? (PotNL or DFO)
2) If you equip Bracers of Fiery Night, what piece would you have to sub back in for the missing Hit? (Valanar's Signet Ring? Amulet of Silent Eulogy? ...?)
Discuss.
(Note: Bracers of Fiery Night provide more haste, and a Red Socket over the Leather Bracers: Phaseshifter's Bracers, which have more crit, and a Yellow Socket)