I was using an 8M and wanted to try something a little shallower. The 8SV is a medium shallow cup but the V shape makes it feel smaller as the drop vertically down from the rim is less than the M cup.
For me the result is faster response, more focus and projection, easier high register but the trade off is it is less forgiving when the embouchure tires and becomes less efficient.
Although with the right approach it could be an all round piece for Bb trumpet I feel it really comes into its own on piccolo or soprano cornet where it can make life much more comfortable.