As I said, if you plan to got to battle, the best armor is always preferable. If you plan on doing other things, then probably not.
The thing is, I don´t see SG/Exanima as a game where "rogues" and "assasins" are a form of combatant. An assassin is someone who is supposed to eleminate a target person, and these things are usually not achieved by busting down the door swords blazing, but by a pillow on the face, a quick thrust with a dagger or a drop of poison. An assassins first goal should be to look unsuspicious, so he would probably wear a peasants or servants clothes. The only time he would wear armor if he would pose as a guard.
Just try to free your mind a bit of RPG clichees where assassins and rogues ar possible classes which spin daggers in someones face, and ask yourself: If you found yourself in a situation where someone swung a blade or a club at you, would you feel more comfortable in cloth and leather with a dagger in your hand or encased in steel with longsword?
