Andreas Maurer wrote:
For approximately 30 years the performance of gliders has hardly
advanced at all and yet we now have the tools (computer programs) and
much stronger materials (carbon composites) to surely advance the
state of the art of gliders.

Hmm... do you know something that noone else knows?
30 years ago the maximum L/D was about 46:1, now it's 70:1... I would
dare to call this anything but marginal.
Or standard class: LD went up from 35:1 to 48:1.

Absolutely true.

But let's not commit the all too common mistake of "maximum L/D"
fixation when it comes to performance.

I suppose we can agree that "performance" should include
everything that contributes to improving our cross-country
speed under varying conditions. And maximum L/D is only one
of those factors.

It is just as important to consider L/D at varying speeds.
If we do, we get even bigger differences than the above.

(eg. what was the best L/D at 180 kph 30 years ago and compare
that to today's performance).

Cheers CV