I guess we really cannot rely on what stores say as probably they are under some sort of non-disclosure agreement. Have you noticed how OcUK and especially Gibbo became quiet about these? They even changed the Out of stock status to Pre-order without dates. BTW, the delay is due to AMD screw-ups. The monitors were tested by the FCC in Jan and initially they were to be released in Apr which is indicated by FCC filing and the fact that FCC made all the documents public. Rumour has it that a quite few manufacturers are ****ed at AMD. Samsung is quiet at the moment but apparently it is considering for next year a G-sync version. (Again, this is what I was told who actually was spot on with the dates. As it stands, they want to see how this will be fixed and whether it will bring the financial benefit they expect from these models.)
I also saw those mid-June dates on various websites and they do change almost every day to a later date. As you probably noticed there is no set date. Even when you look at the latest Samsung announcements even Samsung does not state a specific date. BTW, I love these models as Samsung announced these at least 4 times now! Therefore, what I heard from a good source which is the end of Jun or early July a while back looks day by day more of a correct date.