A difference between 6max and FR that hasn't been mentioned yet is the required level of nittiness. In FR, a VPIP of 16% is LAGGY and over 20% VPIP is maniacal. It's a game where "tight is right", and adequate patience is the skill most micro-stakes players lack.

(That's overall VPIP, not positional VPIP. Positional VPIP's will be higher in CO, BTN, SB, BB, and progressively lower with distance from the BTN.)