We tested one of Harken's prototypes for those blocks, but it was a different configuration. Honestly, HANDS DOWN the best conventional main sheet system that I've EVER used!! I've not tried the ones that they are selling, but I have a hard time believing that they're better than the prototype that we have. I'm sure that they are because that is the design they went with, but... The Harken's with the "Mickey Mouse" blocks on the side can't hold a candle to the new ones.
When Harken sent them to us, they gave us some info on the efficiency of the current blocks vs. the new ones; it was amazing to see how much work is lost due to friction in conventional setups. I built a 9:1 internal cascade for my A-cat and REALLY like it; the difference seems to be efficiency and smoothness.
I think the biggest difference is that because of the increased efficiency, you don't actually need as much purchase with the newer blocks. The ones that Bora is using though can be reaved to a variety of purchases, so adjust as needed for your boat/crew. The prototypes made running the sheet on the big rig Tornado much easier; the toughest thing to get used to was how much more freely the line ran when easing.
Sam, I'm not sure that there is anything fancy going on with the traveler; I read the class rules and thought that system was "closed".