Eric--- The only reason I know something of Rocna's history is because I initially talked to Rocna directly in New Zealand about their anchor when we were trying to figure out what would work best as a replacement for our previous anchor. They told me about the development of the anchor and how it works and then we talked about the best size for our boat.
When we decided to buy a Rocna, I had several conversations with the fellow who owned Suncoast in Vancouver (unfortunately I've forgotten his name although I think it's Chris). At that time, Suncoast only made Rocna anchors to order. They did not make them on spec.
So we decided to order one, Suncoast made it, and when they told us it was ready we drove up to Vancouver and picked it up from the company that did their shipping. It was an interesting visual when we walked in to collect our anchor. Suncoast had just completed two anchors--- our Rocna 20 (44 pounds) and a 200 pound monster. They were sitting side by side on the shop floor, and when I first saw ours I had serious doubts about it being big enough.
Our anchor came with an instruction pamphlet and a manufacturer's call sheet that lists the metal the components are made of, the dates they were made and the anchor assembled, and the name of the QC person.
I don't know much of anything about Holdfast other than they acquired the rights to manufacture the Rocna and subsequently moved its fabrication to China, at which point fabrication in New Zealand and Vancouver ceased. I assume Holdfast moved the production to China in an attempt to reduce the price of the anchor, which at the time was much higher than the cost of most other anchors. Our Rocna 20 was just shy of $1,000, for example.
The Canadian Metals info regarding moving Rocna fabrication to their own plant in China came from press releases on their website.
I don't know much about any of the other brands. I recall reading that Manson initially tried to interest Peter Smith in some sort of partnership and when Peter refused, Manson stomped off and did his own thing, altering Peter's design enough to avoid any patent disputes (or maybe he didn't avoid any patent disputes, I don't know).
And I know that the Bruce anchor is based on his designs of very large anchors to hold North Sea oil rigs in place, but everyone knows that.
The XYZ, Fortress, CQR, Spade, etc I know nothing about in terms of their history or development.