That's a very good explanation of the different designs, JM. I wanted to add an interesting aside regarding AT's "Dual Magnet" design.

During the 70', when AT wanted to import Japanese-made phono cartridges into the U.S., they faced an enormous obstacle: Pickering, Stanton and Shure held a large array of patents on the single magnet design, and as such, none could be imported into the country.

AT, in a move of marketing brilliance, took a clever approach with the "two magnets are better than one," simply to avoid the patent obstacles. There was never any real benefit in the dual magnet design (the largest claimed benefit was increased channel separation, but Pickering and Stanton specs were far superior to those from AT at the time), and in fact, it actually increased effective tip mass, but AT set the standard in the industry for marketing brilliance. They took their biggest obstacle, and turned it into their sales story. Brilliant. Just brilliant.