can anyone bring forward facts supporting that a Discus2 performs
better than it's predecessor Discus a/b or CS?

Just my impressions from the standard class nationals this year. The D2's were
going well, the only D1 in the contest, didn't seem to stay with the pack in
glide. The D2 uses a thinner airfoil and this may be the edge. Having said
that, new ships are all tuned up and perform at their best, older ships (D1)
aren't always that tidy. This one was a bit worn.
JJ Sinclair