hmin
This is the example from inside C2. My character sprite is 256 x 256 1:1 ratio. You can see from the prior screenshot, compiled with XDK the character is blurry, as is the SpriteFont. Compiled with CocoonJS (same project properties, on low for fullscreen scaling), its clear & sharp like my preview on Chrome PC.
As I've said, I think I understand now why its occurring, since CJS will default to Scale Outer when set on Letterbox, whereas XDK actually do the Letterbox scaling when the screen ratio doesn't match the layout ratio (in my case, its 16:9 in C2 being run on a 16:10 device). So there could be differences in the scaling mode used. Otherwise I have no idea whats happening.