^^^ Sorry to hear your player is busting your hump, kindms. Can't speak for other models and generations, but I have a 2nd gen X5 that's been very good to me so far. No issue with gapless playback, and it reads etree conventional naming without a problem - plays them in proper order and doesn't hiccup on any "odd" characters that I've used (slashes, semicolons, ampersands, etc).
After being conditioned by years of iPod use, I've noticed that the FiiO DAPs definitely have their idiosyncrasies and the interface isn't as slick and intuitive as the Apple products, but the additional functionality and sound quality are leaps ahead, IMHO.