Saltyshaw, I had an issue with my old flats boat porpoising as well and had to use my bennett tabs a lot. Talked with guys with same boat but with different power 115 (me) vs 150 (them) and ask if the boat porpoised. They said it didn't. That could be a prob IMO.
My new sled has lenco tabs and I don't like them. Noisy and color starting to fade on the unit.
Talked with a guy at Power Tech! And he informed me that my previous problem could have been helped with a different prop. Maybe you could call them and see what exactly they could do. This is just my opinions, just offering help.