I own both. I hunted with the "brown" one in October, and the "grey" in November. They are an excellent product, and look just plain COOL!
I also use them during our gun season, and they compliment my cap-lock and BP equipment well.
If you are going for the heavy-weight, I suggest up-sizing to allow layering under it.
I hunt open deciduous woods and I think the grey model is excellent for tree stand hunting once the leaves are down as it is light in the skyline
Get either one, you won't be disappointed.