Today, I moved the weights to 10 and 2 and tried to be as precise as possible to achieve the same twistweight. No matter how I shifted the weights around 10 and 2, I could get a predictable launchangle. No comes the interesting part. When attached the weights to spots around 10 and 2 where the launchangle was least unpredictable, I added 12 grams total also at 10 and 2 (on top of the weights), the launchangle, speed and depth were constant again. This makes me believe that with higher swingweights, higher twistweights are needed to generate a constant spinrate across the face from 3 to 9.
Estimated final specs. 437grams, 39cm, sw.600+, so not very playable obviously.