Hi Moin,
I don`t have an operating scanner*, but this is a summary of what Steve tells on the "Krabbe":
It was felt that an helicopter would fare better as a torpedo carrier than airplanes. The helicopter could complement and eventually replace S(E)-boats ( making four equivalent to that kind of boat ), as well as supporting commando operations. Operations would be carried by 8 "Krabben", one leader equiped with radar ( range 10Kms ), two "Flak Krabben" each equipped with at least one 20mm quad, and 5 torpedo carriers sporting a single torpedo. Apparently the "twinning" of 2 Fa223 would be just an initial step towards a novel airframe.
Kyrill Von Gersdorff`s book on german helicopters adds other data, just refering a transport role: span 12m, 1500kg load, 2 seats, but states there was a project for a torpedo carrier, much on the line of the "Krabbe". They could be the same, only with different missions.
* Steve`s book does not include a sketch of this project. For that our guys in the forum could post a scan from Kyrill v. Gersdorff or Manfred Griehl`s books.