yup this is very similar to what I ended up with:

    -- open Chrome Canary with a specific named Profile
    function canaryWithProfile(profile, url)
      local t = hs.task.new("/Applications/Google Chrome Canary.app/Contents/MacOS/Google Chrome Canary",
      nil,
      function() return false end,
      { "--profile-directory=" .. profile, url })
      t:start()
    end

    -- open Chrome with a specific named Profile
    function chromeWithProfile(profile, url)
      local t = hs.task.new("/Applications/Google Chrome.app/Contents/MacOS/Google Chrome",
      nil,
      function() return false end,
      { "--profile-directory=" .. profile, url })
      t:start()
    end