When you use the normal library function - if you choose Artist, rather than then displaying Album (from the artist you've chosen), it just throws you into a full file list of every song from that artist. And not in album order either - instead in file-name order. So if you have multiple albums, and your tracks are 01 - songname, 02 - songname etc - it currently shows al the 01's first, then the 02's etc.
Easily solvable by just using folder mode - but it is a software issue - and I'm pretty sure that James and his crew will get it fixed.
It's in my review (+ some pics) if you're interested (http://www.head-fi.org/products/fiio-x5-high-res-portable-music-player/reviews/10368)
Yes folder mode is snappy and easy to use for me personally since I am quite OCD about tagging and file management.
The beauty of the X5 is the overall neutrality with a slight tinge of warmth keeping the attack smooth particularly in the treble without loss of articulation of extension. The HD600 loves that.