In this day and age, it is unacceptable that a portable DAP require the user to reorganize their music collection, and then use folder view, because the basic menu functionality of the device to sort by artist is terribly thought out and designed. The Creative Zen Vision M I bought in 2006 had a UI that was 10x better in every way (including searching by artist) than the Fiio players.
The Fiio players sound amazing, no question about it, but their UI is stuck in the stone ages. Also there is the fact that, at least on the X3, there is a library limit of 5800 songs and the player cannot properly display album art; it zooms and crops the art on the display. In the case of the latter, yes I have a DAP to listen to, not to look at, but if it is going to include the capability to display album art, then a user should expect that that functionality will actually work properly. And the scroll wheel is just terrible; the fact that I can generally use the buttons for 90% of navigation instead of the wheel is the only thing that has kept me from ditching it altogether.
I'm getting ready to get an A-17 to replace my X3 as a portable player simply because of the shortcomings of the UI and some less-than-adequate aspects of basic functionality. Given that my DAP is strictly for use as a portable player, and not as my home stereo, I'm OK if I sacrifice a bit in terms of amp power and SQ to have a smoother functioning player when I'm on the road or out and about.