Is POET like the above? Kinda is. Does it really need to be? Once the biggest players and most sophisticated mid-level (think MuliLane, Adva) companies, plus the newcomers that are CAI or the like, have cast their votes, what is there to do, but get in the queue and design in.

I share your concerns, thought process and conclusions.  There are a couple of other issues that also help me sleep well on an irresponsibly large share of my net worth in POET.

1.  The 30+ patents (and no doubt others pending) give me comfort about Chinese or other copycats.

2.  As we discovered with the reluctance of most telecom companies to adopt new technology for 400G, this market is EXTREMELY conservative and does not lightly swap components that "ain't broke".  This makes it very difficult for new players to break in, but once they become the "de facto standard", this conservative attitude benefits the first mover.