I `ve not sailed Serenity but had many years sailing/racing Div 2. In light winds they were unbelievable.In any winds they went upwind as good as dinghys which we had to race against.(We always lost on handicap !! but it was a dinghy club) Cant really see how they could have been improved on. But it was a nightmare in rough water.
Me and a mate once set off to sail around an island off Abersoch (Wales) Ride out was fine; into wind and against swell.Coming back terrible; sailing on a run with rolling swell !!! Mate on his Div1 coped fine; I struggled and was close to giving up.