plukcc: part of the goal of J1772 is that the EVSE will not energize the high-voltage cable until the vehicle is ready. I think that is less of a concern with a portable EVSE, but that may drive a decision to locate the EVSE power electronics closer to the wall plug.
Personally I'd rather them integrate the power electronics into the gun, and provide swappable ends at the plug for nema 5, nema 6 (or the international equivalents, for you lucky bastards that can pull 3 kW out of a standard socket).