StreamOfTheSky
Adventurer
The Dervish is a decent class, probably stronger overall than Duelist. Still, front-like combatant is not how I would describe it. Also, to synergize Swashbuckler with Dervish, you have to take Weapon Focus (scimitar), which grants you no immediate benefit. Also, Dervish requires Combat Expertise, but their elaborate parry ability does not kick in when they use that feat.
Those are good points, though I still think Dervish is the better choice. You are kind of wasting a feat on weapon focus (scimitar) until you enter Dervish, which is why you should take that as late as possible. Alternatively, if your DM allows retraining, retrain it from whatever weapon you use pre-Dervish. The Elaborate Parry not explicitly working with Combat Expertise, even though that feat's required to enter the class to begin with, is absolutely annoying. Enough to make me want to scream at whoever wrote up the class for sheer idiocy. My group noticed a lot of cases where abilities only triggered off of "fighting defensively" and houseruled that you could use them with Expertise as long as you took a -4 or greater (the penalty from fighting defensively) penalty with Expertise. If your group hasn't made any such houserules, you can still always fight defensive AND use expertise. Granted, -2 TWF, -4 defensive fighting, and -1 to -5 for Expertise is a lot of penalties, but between full BAB and the Dervish Dance attack bonuses, you can still generally hit with most attacks. In any case, Elaborate Parry is a small benefit of the class, not even gained until late into it, so it's not a major loss if you never use it.