Hi Alex,
This would suggest that the flows/losses were greater off the top of the fuz than off the bottom in KE before the fence was installed - which makes sense !.
This is all pointing to a suggestion that flat sides , c/w fences, are the way to go - maybe even slightly concave.
The fuz should be a slice out of a constant cord wing with fences added to compensate for the short span - not pretty .
The current rounded top and bottom decks are just reducing effective span.

Brian