Hi, ZD – since you mention that you actually wanted brown, I would agree that using brown instead of grey would make for a much nicer combination.
I used brown as the base colour for my own tartan (which might never be woven or registered!).
And possibly the green is a little too pale.
But overall it is an interesting concept (especially if you make it symmetrical) and I would love to see it in woven form.
Regards,
Mike