I am close to switching from rMBP to rMB but would be grateful for info on one issue. My main external USB drives at present are bus powered Seagate Fast 4Tb USB3. These are RAID devices containing two 2Tb drives so I suspect the power draw is higher than usual (unsurprisingly). My late 2013 rMBP drives these quite happily connected directly. Any idea if the power available at the USB-C port of the rMB is similar to an rMBP such that it would power one these without needing to be plugged into the wall? Thanks.