Doesn´t the self standing support alleviate hull an beam stresses enough to require less reinforcement, resulting in less weight and cost?
Yes. Especially the bows can be build lighter although some of that advantage can also be had by installing double forestays.
The main benefit appears to be that the hard points halveway between the beams is a lot better position to lead the loads to then some bow bridle hard point. Especially when the daggerboard bulkheads are in the same neighbourhood. This allows a designer to use the same reinforcement for more then 1 purpose. And because the trampoline is TENSIONED the strut forces trying the push the hulls apart are significantly reduced. That is one of the beauties of the depicted unstayed mast design. The other is the almost complete negation of mast step loads on the mainbeam, voiding the need for any dolphinstriker. In fact the mast step pulls the beam UP slightly instead of pressing it down.
I haven't done a full comparison of both proposals so I don't really know the net result in the way of overall weight etc. But you'll be surprised at how elegant the depicted unstayed rig is in the way of construction and loads.
Personally, I really like to overall simplicity and clean look. Two of the things I also like about the Laser dinghy.
Also, doesn´t the more flexible self standing mast make the boat easier to handle, even if a bit slower?
Only when designed right. That is one thing I learned with my 4 individual class 5 rigs (4 sails and 3 masts). The newest mast and sail that I bought together as a set are noticeably better in feel and speed. They are just a joy to sail. But the same can be said for any mast and sail combo, also of stayed rigs.
I don't really know if the unstayed rig will be slower. For one thing it may turn out that going dead downwind is faster on the F12 then gybing downwind. Just as with the H16. The unstayed rig can be boomed out completely; not possible to the same extent with the stayed rigs. It is hard to predict which will be the faster mode. But I can be said that the unstayed rig may well be faster and more attractive then many are giving it at first glance.
I always remind myself of the Class 5 landyacht example (unstayed rig) when compared to the Class 3 (stayed rotating wingmast rig with more sail area). Over the last 20 years the class 5's have become so fast that it is scaring away to lesser pilots and it is not at all far off the pace from the King class that is the class 3. The class 5's already have left the One-Design Standart class (unstayed but more area and camber inducers) in their wakes for quite a while. Such was the development of that very simple sock sail principle without camber inducers on a discretely tapered unstayed mast made up from plain alu tubing.
For my own use, I'm very willing to accept any performance loss (if any exists) because of the other advantages. I trailer about 3 to 4 landyachts each time I go and the class 5 is by far the most practical craft. So easy and quick to rig and such an impressive performance that I feel absolutely no desire for a more performant rig. And that was the experience of a large group of class 5 sailors and they started the simplified Promo class using cheaper and commonly available components. This reduced the overall speed somewhat, but that was also the intent. Screaming over a rough beach at 60+ mph (100+ kph) is darn scary at times. Much more then doing it at 50+ mph (85 kph). Mind you the rigs were left unaltered ! All the speed loss comes from the much smaller wheels and thicker tires. Actually these also allow you to drive over less compact sand and entlarge your course.
Anyway, whatever the setup I'll buy at least one.
Best of enjoyment !
Wouter