I think this is exactly what originally asked. Thus, equal weight gliders, the one with bigger wing area (reduced wing loading) can fly slower and gain altitude better in weaker thermals compared to the glider with a heavier wing loading.
Then again, you WANT wing loading in the case of a ridge where a heavier wing loading glider helps. This from a guy that has time on the PA ridges at max @9lbs in a ASW-20 A and C, vs. heavier 20 B's.
Bigger wing area also adds to surface drag which hurts performance. There is a reason the term "light wing floater" was coined.