Here's my recommendation - use another class as the base for high Dex characters. I just had a look through all of the existing fighter archetypes, and they're all lacking in some essential class features. Notably: evasion, decent reflex saves, and uncanny dodge, let alone improved versions of the same. Furthermore, monk makes up for the lack of armour by allowing you to add a second stat to your AC, and also improves it over time.
Fighter levels are like tofu - they'll absorb the flavour of everything else you're cooking with. If the players only want fighter levels for Weapon Specialization, that just takes 4 levels. Heck, as Enkindu said above, you can even get access to it through a monk archetype that gets rid of a lot of the wuxia stuff that you don't want. You'll get a better result making other classes more fighter-like than going in the other direction.
-blarg