Had the X3 for two weeks now. It's been finals time so I haven't had time to do any critical listening, just enjoying the music. Probably log about 2-3 hours a day on average.
I received it with v1.3 firmware? Can't remember 100%. Did the initial charge, formatted a fresh Sandisk 32gb card in the X3 and loaded up the newest firmware at the time which was v2.1 or something thereabouts. Run MP3 and FLAC for all tracks.
Flawless performance so far. Not a single freeze or glitch related to the player. I have gapless on without any issues. I use Memory play, tried both track and position. Currently it's set to position and resumes without a hitch.
The only issue was two mp3 tracks downloaded from soundcloud that had awful tags. A little editing fixed that and everything is working very fantastically.