So far, I think I prefer the Colorfly C4 as a desktop DAP.
The C4 packs features and a product page full of bells and whistles as elaborate as the X5. But the ALPS pushrod, simple - but laggy - UI, SRC, and just feel of it is very good.
The sound of the two units are quite the opposite of what one would believe. The wooden looking C4 is a lot cleaner than the metallic and industrial X5 which is a bit warmer. (NOTICE, these impressions are not set in stone, no real comparison was made. I used two different IEM's on the players)
The X5's UI can be absolutely amazing. But some imperfections in the firmware and its recognization of very fine scroll movements, along with some movement bugs in the X5 do put a damper on things. The C4 gets a free card on this one despite its laggy UI due to just how simple it is.
The X5 wins in intimidation though. I have never gotten excited from 'looking' at a unit I review. I didn't get any 'hype' from the X5 pre release or anything really. Heck, the day I got it in my door. It sat on my desk for a few hours before I decided to get off my butt. Here I am now, sitting, and every time I see the X5, it sends shivers down my neck due to just how amazing it looks and feels.