.. It is an interesting concept of using the Vang in place of a traveler when going to windward. When one looks at the huge forces of the Vang on the backside of the fulcrum pivot point to hold the boom down, along with mid-sheet boom (vs end sheet boom) mainsail adjustment, I can see a few problems. ... We went to few of the sailboats in this Marnia to look at all the designs that are here. Great discussion and heated at times. My vote is still with a traveler.
Even with a traveler, when going windward, I tighten the boom vang.
About the several designs, I would like to point out that some manufacturers have the boom control on top of an arch without or with a small traveler (Malo, Tartan) while others use the control on the traditional place for a cruiser (front), with or without traveler. It seems that there are two different discussions here, regarding cruising boats:
1- The best location of the boom control line.
2- The best or the more practical system to control the boom: To use a traveler or to use a system that makes the traveler almost redundant and it's easier to work with.
I have not sufficient information for having a valid opinion, but it seems to me, that regarding the location, you have a better control and have to make less force if the control line is perpendicular with the end of the boom and that is what happens when you have it on the top of an arch. That location offers another advantage: It is not only on the perpendicular, but also the vertical distance is a lot less, if we compare with the traditional location.
It seems to me that Beneteau technicians seem to think that the advantages of the location are more important than the disadvantages of not having a traveler.
The preliminary drawings of the Tartan 43 appeared with a system similar to the one mounted in an arch (it was mounted on the house top). They now offer the boat that way or with a conventional location, but it seems to me that the preferences of the boat Architect went to the solution that was presented in the first drawings (it has also a small traveler on the top of house).