Sometime back, while my rig was on back order, I asked if anyone had used Icom programming cables with it. My rig finally arrived, as did shortly thereafter new firmware and most recently a memory cloning program. With that, I have been able to test both the Icom OPC-478 and the RT Systems CT-29A cables. (Both need a stereo 3.5 mm to 2.5 mm adapter, plus the EDS-10 adapter which breaks out the Alinco connector to separate microphone and earphone connectors.) In both cases, I have found that they work perfectly for both memory management and firmware upgrade. If you already have a similar cable, you can probably get by with a $4 adapter from RS rather than a new $55 cable.
Unfortunately, the DJ-G7T is not so far proving to be an adequate satellite rig, but that is another issue.