Hi all- I'm interested in getting a rMB but curious to know if it will do what I hope it can.... I have a 2009 mini display-port equipped 27" imac. I would hope to use it as a second display for the rMB, with the imac in target display mode. If i use apple's av multiport dongle, would I be able to successfully send the video signal to the imac using an hdmi to mini-dp cable? Would it come in as 2560x1440? Has anyone tried this? thanks!