Actually I didnt submitted it yet, and this is exactly why - I wanted to hear some opinions, maybe someone spots at the last moment any issue I overlooked, like you did.
Yes, the atmosphere noise needed some tweaking, this one below looks better
Still is there some minor noise, but on the other hand I somehow like it, reminds me that digital camera grain (especially when pointed against sun), which I think slightly adds feeling of realism to the image rather than overly smoothed and too perfect render.
About the snowline, I now played with it a little bit, but Im not that much familiar with Fractal Breakup node, and there is no time for random attempts with values. So I just adjusted it like this, breaks a snow surface a little bit.
Here you can see both raw render and final result, which is just slightly adjusted and I like it like this
Now I submitted it do Danny´s email listed ant NWDA´s site (thats where I have to submit it, right?)