This player sounds really exciting. As it stands, I'm not 100% impressed with the current options I have for upgrading; each player being considered is good and would fit most of my needs, but there is always some serious issue or two I have with each.
As for the upcoming FiiO X3, I can honestly say that I wouldn't bother considering it if it lacked gapless playback. I'd also be pretty disappointed if the battery lasted less than 10 hours with lossless playback, as there are those busy days when even my iPod gets fully drained. Anyway, here's a short list of what I'd like in a player:
- Gapless playback = must-have. Most of what I listen to are live performances or continuous mixes.
- Good battery life (10 hours using lossless should be the minimum, I think) and/or easily swappable battery. For me, 15-20 hours would be good for a music-only device, anything more is awesome.
- Clean, quality line-out (preferably 3.5mm, but avoid use of a specialized dock).
- Sensible and responsive UI. A poor UI could make me look elsewhere.
- Drag/drop for file syncing. Mandatory software for syncing is annoying and restrictive.
- File/folder browsing, so I can organize my music my way without worrying too much about tagging.
- Lots of storage space. I take as much of my music collection with me as possible, so I prefer as much built-in storage as possible. Expandable storage using SD cards would also be a HUGE plus, but I still want lots built-in.
- FLAC support.
- No gloss. Not really a feature, but Jesus do I hate glossy plastics.