this is a really important thread for me, as I'm trying to use 2 x Dell U2713h in a daisy chain.
I bought the, because I need to use the D-DVI to connect a second machine to them like cosmicjoke does which the Apple TB displays can't do, plus there is no way I'm buying a new MacBook pro (as I have done) or a new macpro with TB2 and USB3 to then connect to a legacy looking display that also downgrades thunderbolt2 to thunderbolt1 and usb3 to usb2 at premium prices.
Like comsicjoke I need to use both thunderbolt ports to power both displays, which is a real problem for me as I also need a firewire 800 connection, and the only way I can get this is to use a thunberbolt -> firewire converter, which I can't use if I'm powering both monitors.
I'm pretty frustrated with this whole situation as while I didn't ask apple directly, and with hindsight I should have done, all the documentation suggests that the new mbp retinas support displayport 1.2 - which the dell U2713H also support, so on paper it should work just fine, but it appears to be a software limitation that is being held back instead of a technical limitation