Flu-flus only work for shooting over decoys or when you have enough cover to stalk in really close. If you're pass shooting you'll definitely want to use standard fletching (safety permitting, of course). I've seen plenty of geese dodge flu-flus when flying at normal speeds. Too slow and visible.
I spent a lot of time (and arrows) pass shooting at geese flying over a saddle on a ridge. Used old arrows and buggered up broadheads or cheap Bodkins. If I had a 2 blade head that got bent I cut the tip off and filed it chisel sharp.
Nothing quite like watching an arrow intersect with a flying goose. Even the near misses are memorable.
Be careful approaching a wounded one, especially one that has a broadhead sticking out of it. They're big, strong birds.