I've ridden the Madd and Silber. These opinions are from someone who usually rides a GS board and let them run in Colorado snow, generally packed powder
Madd - very turny, almost needs to turn. Often times I felt like it was going to throw me on my head because of it. I felt that it would be a great board for a day in the bumps with groomed runouts. When I tried a GS turns the board was willing but not happy. I would be willing to have one in my quiver, just not as my daily ride, more of a crowded weekend ride when I need more space than the groomers will offer.
Silber - Willing to make small and large turns, but has a limited range of speed before the board can't keep up. The board always held it's edge well until the nose folded. The nose is to soft and above a certain speed the nose will consistently fold. It didn't throw me over the bars, but felt very limited in how much confidence it would give me. Not a board that I would purchase for the way I ride. If you have generally crowded slopes and don't like to run very fast, it would be a good board.