It looks like Picture Porter/Digital Foci's Kickstarter didn't fly, so the market has voted. After thinking about it, I have to agree, the proposed device was too much of a compromise, too big and expensive, but not capable enough to replace a tablet or computer.
I do, though, have my hopes on a new model from Hyperdrive that I just ordered:http://www.hypershop.com/HyperDrive/iUSB-HD.html
It is a very small and light BYOD (bring your own drive) device with SD and USB host slots, also wireless interface with phones and tablets. Only a very small B&W screen, it is not a viewing device. I intend to install a 2.5" SSD in mine. I will use it for field SD card backup and should be able to view and transfer JPEGS wirelessly on a phone or computer while keeping the RAW files on the SSD. (From what I've read, these wireless devices are too slow for RAW file transfer.) I think it has a hardware button for card copying so it can act as a stand-alone backup without the phone app. I'll keep you posted.