Upload & Sell: Off
All things considered if the goal is location portraits I think regular studio monolights powered by battery/inverters are the best choice nowadays. Reasonably priced monolights and battery/inverters changed the paradigm for location lighting and are less expensive than Quantum or Speedlite solutions.
The logistics of hauling and setting up the stands, soft boxes, etc. are the same (give or take a few pounds of gear) and with the monolights you have a wider range of modifier choices, modeling lights and the option to use wall power if available.
TTL flash exposure control is not a good choice for portrait because just things like the subject turning can change exposure requiring compensation. The exposure and tone of the background will vary shot-to-shot. Even more problematical is when shooting different subject one after another. The differences in clothing can cause large swings in exposure.
It's better to use manual power settings for portraits. Once set exposure stays consistent. It's not difficult with digital, even without a meter. Turn on the fill first. Raise power until detail is seen in a black suit or test target. Turn on key light. Raise it until a white shirt or target clips in playback then reduce the power by about 1/3 stop. The lighting will match full scene range black <> white to sensor range. Any clothing or complexion face will be recorded as typically seen by eye: detail everywhere you'd expect to see it.