Rolf,
I've been out of the loop for some time with a PC melt down and I'm just going through old posts and found this one.
I think you are right on the mark.
Sure when it's blowing dogs off chains the wider beam is handy but how often do we sail in those conditions compared to conditions under 15 knots where the difference is likely to be balanced out by the slower tacking of a wider platform. Then look at the amount of time you sail lighter winds where lifting the windward hull becomes an advantage due to the reduction in wetted surface and corresponding reduction in drag.
It's worth trialling a 10ft beam on a modern hull shape.
The desigbn could have two jib options. A self tacker for bouy racing and larger overlapping jib for distance stuff.
Designing a platform to take a standard T rig makes good sense and is in fact a part of my plan with the additional jib option for distance stuff.
However I think to build such a boat in commercial numbers it will probably have to have an 8 ft beam.
When trying to appeal to larger numbers you can't beat convenience.

Just the way I see it.

Regards,
Phill