We got burned out on AJa products and some of their eccentricities with our systems, and are now giving BMD's ultra4K boxes a try. It comes with a free app called Media Express that you use for capturing from tape machines, using machine control. There's a range of these boxes from BlackMagicDesigns, both more and less expensive, based on the connectivity you need.
We are more or less happy so far, using one of these Ultrastudio 4K units with a Panasonic DVCPro HD deck, but, I never did get anybody in the COWS's BMD forum to answer my noob questions about setting up the software and machine control with our thunderbolt iMacs. Phone support is polite, but so far, not really solving problems for us either.