I have V-pros with no risers and they carve like MAD for skis their size. no need for risers.
risers allow you to exert more leverage on the skis and the skis to exert more leverage on you. it is harder to land if you are a little off-center with tall risers because the ski will be more likely to want to edge and exert torque on you. Risers also eliminate the 'feel' you get when you are close to the ski and feel it flex and move on the snow.
Critical Motion Films