I get Mavericks through not Dev but another Apple program.
Anyway since Mavericks, on both my 2012 13" rMBP and my 15" r 2013 MBP, I could not boot with a USB hub and three drives attached. I'm not trying to boot from one of those drives but from the internal SSD. it has never worked, just sits there with a blank grey screen, so I have to disconnect the USB cable from the Mac and often turn it off and on again to get it to boot, then attach the USB cable.
Since yesterdays latest Mavericks build it boots with everything attached.
Finally.
Anyway since Mavericks, on both my 2012 13" rMBP and my 15" r 2013 MBP, I could not boot with a USB hub and three drives attached. I'm not trying to boot from one of those drives but from the internal SSD. it has never worked, just sits there with a blank grey screen, so I have to disconnect the USB cable from the Mac and often turn it off and on again to get it to boot, then attach the USB cable.
Since yesterdays latest Mavericks build it boots with everything attached.
Finally.