From the Space user guide: With Spill enabled the ‘tail’ of the previous Preset effect ‘spills’
over when a new Preset is loaded. That means that Spill option is available only when the effect is engaged, and not in bypass mode. I think it would be a really nice feature to have spill smoothly fading even disengaging the pedal, especially with long decay reverbs like shimmer, modechoverb, dual verb, blackhole ecc. Maybe I'm missing something?