Ville, if you still have one of your bipes that is hard to handle on the ground maybe you can apply my theory to your plane?? I believe the theory can be used as a general rule but since I have only one bipe to experiment with I am reluctant to go that far at this point.
One of my flying buddies has a bipe that does a lot of left-right left-right during takeoff. Maybe setting both sides of the lower wing for equal ground effect lift and than trim the upper wind for straight and level flight can eliminate this. This will take several flights, doing upper wing trim adjustments between flights, to get the upper wing trim set correctly. It took me five flights. Now it’s a real joy to watch the o’l bipe track straight down the runway, have the tail come up, roll another 15-20 feet and fly into the air.

If you OR ANYONE ELSE try this please let the rest of us know how it turns out.