Gero,
That is the system I'm using. It was one of the key points of my design back in 2003.
Since then I realised you don't need to make a hole in the main beam.

I have also considered non essential stays that could be used only when required to stabilise the mast for heavier crews.

I always intended a modern cat version of the Laser.
In more ways than you mentioned.

BTW:-
We have one of those cats with the struts above the deck at a local sailing club when I was there a few months back.
It was offered to me for $350, not that I was asking.
So anyone not wanting to build a boat and happy with the struts I know where there may still be able to get a boat.

Regards,
Phill