I’ve occasionally tied flies using this method. The main problem I’ve encountered, though, is that it tends to make for a rather lopsided wing, as many feathers aren’t evenly balanced on both sides of the stem. This particularly applies to bronze mallard, which is very definitely ‘sided’ in one direction or other. The fly you’ve shown photographed from above in post #2 uses a dyed feather, which goes some way to getting round this, but I can’t see how you can achieve this with a natural feather. Can you explain further, and do you have any pictures of the ‘wrong’ side of flies tied this way using undyed feathers?