Cloaks do not drop in the Dragon Soul raid. There are a whole bunch of cloaks that are Firelands tier or better which we might have. But really only three of them look good. (And I don't mean for transmogrification.) Those three are the following:
1: Lord Rhyolith's Dreadfire Drape. It's old Firelands and item level 378.
2: Lord Rhyolith's Heroic Dreadfire Drape. It's pretty pimped at item level 391.
3: The Batwing Cloak. It sounds great and has the highest item level at 397.
Okay so what's the problem to uncover? They all do look pretty good. They do, but the Batwing Cloak has less agility than not just the heroic FL cloak, but the normal FL cloak drop. If we assume non-heroic gemming, then the stats work out like this:
1: Lord Rhyolith's Dreadfire Drape: 312 agility, 138 hit, 95 mastery
2: Lord Rhyolith's Heroic Dreadfire Drape: 341 agility, 158 hit, 113 mastery
3: The Batwing Cloak: 301 agility, 162 crit, 176 haste
Agility aside for a moment; The trick here is that the Rhyolith cloaks are laden with mastery, while the valor cloak has large amounts of good crit and haste. My napkin math says the valor has 338 points of good secondary stats, while the normal Rhyolith cloak has only 138 hit, 57 mastery, and 38 crit ... call it maybe 200 good points. So we have a difference of -11 agility and +140 good secondary stats if we use the valor cloak. The highest item level agility cloak has the least amount of agility. Agility is our primary stat and generally worth 3x "crit/haste stats". Because 33 is less than 140, then it is of some benefit to upgrade to the valor cloak. It certainly isn't something to do any time soon.
The heroic Rhyolith cloak however is something to write home about. The biggest issue here is that heroic Rhyolith is a pain in the ass. The napkin math looks like trading -40 agility to get around +85 secondary. Because 120 is not less than 85, the valor cloak is not even close.
The mediocrity of the Batwing Cloak is shown a bit more if heroic gems are used, but the results are the same. Upgrading to it from a Dreadfire Drape is either a very low priority, or a bad move.