Well it's for mass production so, I want to be able to scale up without too much fuss. Even for the first few boards I would much prefer to re flow. It would take far to much time to hand solder those components for each machine.
A plastic holder could realy help speed up manual placement. You could add x small holes in the main PCB to position the holder. I have thought about this idea too, not for the G120 but more for fine pitch SOMS's or BGA's