Ragtop,
I balanced mine at about 150-152 mm. Slightly forward of the recommended 155 mm. I found mine was pretty pitch sensitive a little behind the recommended point. Once I made it slightly nose heavy it calmed right down. Also, with the Sierra gear the geometry is pretty close with the gear far forward to get the correct rake. As it retracts the CG shifts noticeably rearward and the plane was pitching nose up. With the CG a little forward with gear down, as the gear retracts then it is about right on.