It's nice, but I have to agree with two points people gave - Some extra contrast would do it good, and the stock looks smudged...It looks like it's been resized horizontally.
Try replacing it and adding some more dark areas, or if you don't feel like changing it in it's entirety add some Hue/Saturation, Levels, Brightness/Contrast and maybe Gradient Map layers.
Overall it's not a bad sig at all.
And about not entering CX Sotw....Why not enter? if you have some sig that fits a theme or feel like doing one you should enter. Like anything it's not about winning it's just for fun, and it helps you improve. If you think there are better artists here than all the better to focus more work here and learn more :)
