Pingfao,
I like the concepts behind your TH7. Some similarities to what I designed for Lostris.
http://i.imgur.com/H6rGO6V.jpg
The open design indeed would confuse some attackers, and that's the whole point. They underestimate how "easy" it is since it's very open, but then suddenly they start panicking and scrambling to recoup the losses as the battle unfolds.
From her feedback, there was only one breach through the center walls and it wasn't from wbs. I imagine if someone sent in 27 wbs though they should go right through the middle.