Was just finalizing some layout stuff with some test content, and noticed that the comment button doesn't seem to be working:
www.han-river-riders.com/component/k2/item/10-gloves

when I inspect the button in firefox using firebug it seems to be okay, indicated as input, submit form, etc but clicking on it just does nothing.

Same for logged in or out
and commenting is enabled for all

You have positioned the "back to top" container right above the comment button. That's why you cannot click it. It's your's CSS issue.