I think there is a difference between the cfd provider taking orders on it's own books and actively hedging (maybe several times) and either making a spread or providing the appearance of direct access and charging a fee per trade or doing what GNI seem to do (according to one of the posts above) which is to actually perform the trade on the real order book and create a nominal position for the customer and finance it. This is what I thought all direct access brokers did but, thinking about it, they could simply offer a simulation and balance their books as and when they felt it necessary, same as spread-betters.
I still maintain, though, that it's only the actual trades on the physical market (i.e. the hedging trades) that actually affect the market. So unclosed short positions must show up eventually. Or was your original point that Crest is useless because of the time taken for the information to appear in the first place?