Yes it's a very interesting board - I really like the concept, especially when you have tried slapping against waves going upwind with a flatbottomed race/longboard which is very tiring.

Personally I think it is a bit on the large side, as when you have the length you do not need that width, but it might influence that it was developed by a big guy (Patrice Belbeoch). Also in light winds the advantage of such a large dagger and fin will not be that benificial as it create drag at slower speeds - but anyway it would be a perfect match with a SpeedFreak

The key focus of this board is/should be to maximizing performance in light winds, where I think most will have switched to something smaller when the wind picks up - as like the conditions in the video below where it is also tested in higher winds where it also shows the consequences of going at speeds with such a long and large board (the bouncing up'n'down of the nose)

Apparently there are only going to be made 50 to begin with with a pricey price tag of 2900€ (aprox 3800 USD)....

You can read more about the RS D2 and similar designs here
http://www.lbwindsurfing.com/

And a video of it here

I would love to buy one of these, but unless I can see it race with another good race board like the F2 and leave it in the dust/waves it's just talk.  Bring one up to the North Easts to race against all comers and you might see these boards sell. If one could beat me and Dennis I would buy it on the spot. 4 to 12 knots.
$ 3,500+ is a lot to spend for an unproven board.