Hello. Quite interesting this one. Thanks for the remark although I gather that "sofisticado" can be either negative or positive depending on who says it and how. Anyway, to give the cold shoulder to our false sophisticated friend you may try "refinada" (or "esnob" if the text is critical of the guy). On "high-end", that's got to do with the association with the most expensive section of the market (Shorter): "una persona refinada en la cúpula (cumbre) del mercado/a la vanguardia del mundo financiero/etc. Or "de altos vuelos" if you want it more slangy. That's what I can come out with for now, no doubt more choices will pop out. Can't wait for that, gonna be fun! Good picking :)