I guess scherzo like intention doesn't always have to be fast. The form is ABAC as far as the dynamics are concerned.
At one point I use the Super coupler (my terminology) and add lots of stops, then to go back to the original registration. The "C" part is the tremolo, Vox Humana and 8' stops of Man. III, gradually diminishing and finding the key of g to end with.
The so-called solo voice of Man. I uses no reeds, but the amazing Gamba which has a wonderful reed-like effect.