Darrell Nicholson, the editor at Practical Sailor, had to tug hard to get that article where non-subscribers can read it. The PS publisher doesn't like to give stuff away.
Unfortunately, he couldn't get all the accompanying diagrams and tables up there.
I'd like to take the opportunity to point out that wide beam aft isn't the only factor here -- keel size and placement seems to be a big player. And it was a little unfortunate that a Tartan appeared as an example of the modern type (I think that's what they had photos of). It's beamy all right, and has a biiig transom, but Tim Jacket, the designer, seems to have a better approach than some -- mebbe because he's both the designer and the big kahuna at the company and he likes his boats to perform (he also designs the C&Cs). He actually designs a keel stub onto his hulls to help give him the needed area. My wife I "borrowed" a Tartan 3700 a few years ago and had to beat from Tilghman Island to Annapolis in 15 gusting 20. It was very well behaved and even though it was a rainy day and we were on a "train-to-catch" kind of schedule, we both enjoyed the sail immensely.

I learned a lot as I was researching for this article and took a slightly different approach to the center-of-effort (CE) vs center-of-lateral-plane comparison that you normally find in the "textbooks." It helped explain the round-up phenomenon for me.

I'd like to see these issues aired more widely, but I'm afraid Practical Sailor is the only sailing publication that I can think of that would put this discussion in the open.