When considering a spinning reel ,I would look strongly at spool size. I have used ice reels trying to get that lighter option for short rods. The small dia. spools were a nightmare for me .
Is the 6920 more of an ice reel meant more for vertical fishing. Looking at Pfluegers website it seems the 6925 is almost the same size/ line capacity. I think theb25 has more bearings.
Maybe the 6925 is a better match for both the light and ultralight?