Brett and I both read your post and see the plane doing the exact opposite.
That's because of an ambiguity of the description of the maneuver used to flip the airplane over. Some facts (which you probably won't believe, because nicer people have told you different):
Bank angle in level flight won't tell you much about tip weight. The effect of tip weight is greatly amplified in maneuvers. If you see the top of the wing in outside loops and the bottom of the wing in inside loops, you have too much tip weight. If the airplane gets light on the lines in both inside and outside loops, you have too little. You may be overdoing the tip weight changes: two grams is a significant change.
The line reel thing comes from long-ago stunt lore and has no physical basis. You might as well use your hat or a Tom Waits cassette tape.
If your wing has a warp (you said it does, but we assume you meant that it doesn't), a tab will balance the warp for some loop radii, but not all. This is because the wing section lift curve is nonlinear. Somebody here has probably drawn pictures explaining it.
Fiddling with flap area asymmetry has a very subtle effect and not worth the bother for an established design--not until you get tip weight within a gram, anyhow.
There is no physical basis for equal flap area.