I ran a set of the originals with a
150 section rear, standard for the oilhead boxer GS's. This was the pattern still shown on the site in smaller sizes for the standard K60. It had no circumferential rib at all. It was then withdrawn as a 150 and modified to produce the pattern shown in the second image above for the rear and was then called the Scout. This was then superseded by the pattern shown in your top image with a very much bigger centre web linking the blocks.
I suspect that the redesign is an attempt to stop the blocks ripping off the carcass of the tyre under the stress of the big boxers etc. which a few people had complained about. It will also give a longer touring life but I don't know what the downside will be in mud. I got over 7,000 miles from the original design so unless the rubber compound has changed the newest version should give exceptional mileage.
I believe that their website is a bit out of date with the intermediate design still showing as the Scout in the tyre detail section but the new and latest design showing as the Scout in the news section