When I recently swapped over from a BCD to a DGX wing with SS plate I was a little surprised at the weight shift. Prior to the swap I was using about 9-10 lbs. (I always dive with an AL80) so I figured a 6 lb. SS plate plus 3-4 Lbs. With the SS plate I added my standard 4 lbs. and was way too heavy, so I stripped all the weights and I was trimmed out with an empty bottle. I figure most of the mystery weight was trapped air / inherent buoyancy in my old BCD. The point of this is that the weight calculations are not as straightforward as they look and if they are close on paper you may wish to try for a lighter plate. For myself, with way to many donuts hanging on my mid-section, a SS plate works, but there is little wiggle room and if I were to go with a more negative tank I would need to acquire a lighter aluminum or composite plate or be over weighted.