The contemporary of the ASW20 were the Mini Nimbus and LS3/a not the LS6 or
Ventus! both of the latter which where 2nd generation 15m designs - the
ASW20a was 1st generation 15m -Schleicher just got it right first time. If
i'm correct I believe 20B's cannot fly club class (at least in the UK).
DaeC index is the same though for all three - although other national
handicap systems have the 6 and Ventus as a higher handicap.
Anyway you need something like an old standard class glider to win at
World champs level i.e. Std Cirrus - the higher performance gliders in club
class don't do too well - why G.Dale traded down from an ASW24 to a DG100.