I have been looking into building a Double or Triple long Lang. I came across this site: http://www.moderntopbarhive.com/
Pity he calls it a modern "top bar hive" because it's not a top bar hive. It's a frame hive, with a shape that reminds beginner beekeepers of a top bar hive.
The selling points of the top bar hive are that (a) you can make the hive cheaply and (b) you can make the hive without precision. The only important measurement in a real top bar hive is "35 mm" (the width of the top bars). The Roland Reed hive is expensive and it must be made with great precision, otherwise it fails.
Older beekeepers will know that the Roland Reed hive's design has been around for quite a while (similar hives existed in the mid-1850s, even).
If you think it's worth shelling out $500 for a beehive, I'd say: go for it. Will you have success with this hive, as promised? It depends on your climate and your available flow.
The reviews on this hive from a Google search are calling it revolutionary.
Those aren't reviews. Those are newspaper articles written by journalists who are not beekeepers themselves and who fall for the spin after the barest of research into the topic.
His web site claims that bees only build their honey stores vertically, above the brood nest. That's is not strictly true. Bees store honey not only vertically but also horizontally. They store the honey not only above the brood nest but also to the sides of it.
I am thinking that it is VERY similar to the Dartington hive.
I think the Dartington hive is deeper and longer, and the Dartington puts smaller supers on (and puts then on top of the entire hive, if possible).
Or just go all out and do a 40 frame beast with no supers at all?
If you're going to make a 40-frame beast, why not make it with two parallel rows of 20 frames instead of a single row of 40 frames? (and while you're at it, google for "golz beute"). A 40-frame beast in a single row will suffer the same problems as a vertical hive in which you never add or remove any boxes -- they won't fill the entire hive.