Hi Bertrand
There are no improvements in respect to the rounded original bow, besides, as you mentioned, that the slanted bow is more easy to build. Waterline length, buoancy etc all the same. Deck is in the negative slant some mm longer that is all. The instruction how to build the rounded version is clearly shown in the drawings as well ass the pure negative version. So it is up to you.
Bernd
Bernd Kohler