providenceH, 

The effect you’re seeing in the video, where the repeats drop off faster with a distorted input, is common. I can recreate this using any distortion pedal followed by an analog delay pedal. 

It happens because a clean guitar sound is quite tonal and correlated with a delayed version of itself. This causes the feedback to re-enforce the signal on each repeat, so it takes longer to die out. A heavily distorted signal is not very correlated with itself. This causes the analog feedback to have less of a re-enforcing effect on each repeat, so the repeats die out quicker.

One way to deal with this is to have a separate Rose preset with a higher feedback level for when pre-distortion is enabled.