quite obviously only works at a speed which will give a good flow over the tab-but still little effect in my experience.
However the op is a similar thing to that we had with a 5.5 ocean pro which exhibited all the same problems as it got up onto the plane. Simply trimmed in far too much due to good transom angle and no stops on the saddle bracket. Once the guys got used to the boat it was fine-just dont trim it too hard in at the outset. The amount of down trim available due to the transom angle was however a godsend when head on into rough seas