I quite like the class - Duelist-like characters have always been close to my heart, so much so that I crafted an encounter with a Duelist that is specifically designed to be a one-on-one fight (literally, the big guy with the sword in your party is challenged by a duelist to a one-on-one fight to resolve a matter of honor). I also like that Sneak Attack damage counts toward meeting the prerequisites of Duelist, because it always seemed to me like Rogues were meant to be Duelists, especially in Pathfinder, where Finesse Rogue is given as a Rogue talent. I also love the Duelist's Challenge, which seems like the point of a Duelist, but is usually pawned off on some other class (Cavaliers get it instead in Pathfinder--what gives?).
Glad to hear that you like it, especially coming from someone who enjoys the archetype. I was worried some people might find the challenge a bit jarring. Speaking of, how do you feel about the dimensional anchor within reach portion?

I like how Uncanny Dodge was worked into Fancy Footwork's text, but almost wish that it would be placed on its own as a standalone ability--if for no reason better than to grant Improved Uncanny Dodge to characters who already gain the benefit of Uncanny Dodge through levels in another class (Rogues, Scouts and even Barbarians all get Uncanny Dodge before they make it to Duelist, and get no secondary benefit from Fancy Footwork as such). Alternately, some amendment to the text to account for that (as is seen in the SRD text for Rogue and Barbarian already) might be nice.
I could put it into a separate ability and allow the scaling, but really, I'm not sold on the Duelist actually needing improved uncanny dodge. It's one of those things that would be nice, but not particularly necessary. On the other hand, Uncanny Dodge is one of those things, as someone else put it, is necessary for the class to function. It wasn't put in to be an extra power boost so much as to ensure a duelist doesn't get splattered because he didn't have it, if that makes any sense.

I would also make Combat Reflexes a reward for Duelist as opposed to a requirement; doing so would allow characters that aren't Humans or Fighters to PrC into Duelist before level 10 (a race/class combo that offers no bonus feats won't get this until level 9, even if they meet all the other requirements by level 5). A Fighter can still PrC into this at level 6, as can a Human Rogue, but it's not too steep for other characters. It also gives Duelist more of an incentive, though I understand if there are balance issues that arise from that.
I can see your concern with a non-fighter having trouble entering the class... what if instead of making combat reflexes a bonus feat and taking it off the prereqs, I bumped the prereqs down to requiring dodge instead of Mobility.

That way a non-human non-fighter could go 1) Weapon Finesse 3) Combat Reflexes 6) Dodge, and qualify at 6. There's nothing in the class that really requires mobility, it is merely fitting, on the other hand, combat reflexes is a pretty central part of making the class work, and I'm leery of handing out further power increases, even something as small as an extra bonus feat.