An alternate POV: If the iBasso sounds significantly better than the X3 or X5 (which is certainly a possibility, and maybe even a probability given the SQ of their previous releases), then I'm not sure they will really be direct competitors. If iBasso felt that their device offered a noticeably better sound, they would almost be better off bringing it to market first, as it would prompt FiiO to either delay the release of their product while they work on improving SQ or possibly to reduce the price point so that it did not directly compete with the DX50. Also, establishing a beachhead at the $300-400 range (hopefully) could be a positive thing, as any other device that comes along in that price range would be compared to it (the DX50).
Conversely, there is a danger in waiting too long-- if you wait long enough for other competing products to be announced, you give people more options to wait for; your competitors can have time to work on improving their designs; the natives (=us) can start becoming restless and irritable; and your product runs the risk of missing its moment and being delayed into being inconsequential.
Ultimately, if you release a player that strongly outdoes competitors with its SQ-to-cost ratio, you'll have a winner on your hands. I just hate waiting and would like to provide any rationale possible for them to release some @#$% information ;)
All IMO, etc.