I personally think you should have Dead Wood be left as Darkness, because it reminds me more of a haunted forest then of a decaying tree, since it's a dead Ent.
I also think that you should keep Dead Wood as the card in the bazaar, because the point of the card is to bring it back to life as an Ent. With an Ent, you're looking at "Oh, I hope it doesn't die, but at least if it does, it'll be alright"
with Dead Wood, it's more "You might think your safe in the dark of the night, but these trees come to life."
Not sure if I really made my point, but meh.