It does not make sense at all for that Talent to have a requirement of Expert Marksman 1 instead of Scoundrel 1. Scoundrels are the ones who will be moving around in the middle of combat the most.
Rangers should be far away, and they get Quickstep and Tactical Retreat earlier than Rogues get Cloak and Dagger. (I think.) This just makes Rogues spend an extra ability point for no good reason.
I strongly disagree. For one, I don't see Scoundrels needing to move around in combat any more than any other melee character does. How often are you disengaging from melee range as a Scoundrel?
More importantly, because Rangers want to remain "at range" is precisely why this talent is best suited for them, as it comes into play every time the AI decides to run opponents up to the Ranger's position. Getting slammed by attacks of opportunity every time the Ranger attempts to move away is a nightmare, and Tactical Retreat has too large a cooldown (9 turns?) to expect it to be available every time a melee opponent comes near a Ranger.
