I would think the Mythos speakers would be the better way to go for sq. Are you choosing lower profile speakers for any particular reason? If they're going behind screen I think you can find some more pocketbook friendly and as good, if not better quality speakers. The mythos are nice, but they're pretty pricey IIRC.
I'd avoid in wall/ceiling if at all possible unless they're effect speakers. Never for the front 3.