OP, I like your ideas with the exception of one thing. If the Chemist class is one of Musketeer's branching jobs then I want the other option to be a pure Ranged-DPS job akin to how Dragoon and Monk are with an arsenal of weaponskills along with DoTs, buffs and debuffs and no supportive party buffs that would hinder your damage output by -20%. If Chemist is not a branching job then I wouldn't mind the Gambler so much.
This stems from a personal desire to have a pure DPS ranged class with a ranged DPS limit break since Archer doesn't branch into a Hunter/Ranger(yet).