I'm waiting for my rMBP and am in need of an external drive for the beauty that is coming to me soon. I'm kind of at a stand-still. Should I go with the expensive thunderbolt drive WD MyBook 4TB or are the USB3 speeds just fine for editing photos directly from the drive? I'm shooting a D800 with uncompressed raw files at around 70 - 80Mb/ea. I'm not too interested in being slowed down by the drive as I want to keep the lightroom library on the external drive. Any help is appreciated.