Many thanks for the info.

I am well aware of the roll of contractual consultant. I have done a bit of "invention for hire" work over the years including many startups and generally took the cash over stock. Most of the time it was the right decision as most startups don't make it (but there were a couple that I look back a bit whistfully on).

However, if this very long in the tooth "startup" ever pops, I hope the key inventors manage to get a share in any future uptick for their contributions over the long haul.