I have a couple of thoughts on this one (for what they're worth). First, i don't get why the opinions of the folks at Superior Threads are so often cited as authoritative (or superior). Second, Harriet's daughter is doing a master's thesis on the physical qualities of thread, which should be at least as scholarly, or perhaps even more credible, since her main business isn't selling thread. It will be interesting to see the outcome of her work, i think.
Hugs,
Charlotte