While it's certainly true that hot shoe flashes are underpowered for 6x7, I can get f/16 at 1m from the mini softbox. So it's quite usable in a pinch, especially at ISO400. The fact that you can sync the flash all the way up to 1/400 really helps when you're out with strong ambient.

For example, at 2.5m, balanced light , at 1.5m, over powering the sun.