OP_CHECKSIGDATAVERIFY seems like a useful op-code for bitcoin.  Has this, or something similar, been brought to the attention of the developers before?

As you pointed out, this system can work with E being the only link between parties (a main hub) and escrowing HTLC-style contracts between them.  What I'm specifically interested in seeing illustrated, is a hypothetical scenario where E is a BTC-denominated derivatives exchange escrowing contracts between users with payment channels only directly connected to E.  Furthermore, W's distribution would need to be determined by a live data feed.  Do you think something like that is workable?