Mystic River & Iorveth (Key?)

[jaedenruiner]

So,
Yea, i will often use walkthroughs and other such things to describe these more complicated style games so I can get the most out of the game. I don't need to know how to fight or play, but seeing soooo many interwoven paths (when i have to decide) it's helpful to have a little insight.
Eh, it's Metagaming, but i don't care. :P

That being said, there is a quest called The Mystic River, in Chapter 1, which i thought nothing of until it became clear that Choosing Iorveth over Roche would have affects on this quest.

Apparently, there is a Death to the Traiter quest which is inspired by siding with Roche, and in that quest you get a key. It appears that key is needed in chapter 3 to open a quest for some really amazing armor. (Armor of Ysgrim, and the diagram for Vran Armor)

Is it possible to side with Iorveth and get that armor, or is the only way to acquire it by siding with Roche?