Amazingly it is fantastic, with one acceptation, IMO the Slim Down could have more extension in the low end. Meaning if turned down to 0.0 it cut less lows. Edit: As I look at it further maybe the correct idea is to give the option to add some lows. Maybe a negative setting?
That is a very good idea that goes in line what my findings comparing the KD with real pedals. In general I tend to need more extension in the low end that has to be compensated by using the tone knob or lowering the Mix knob to let thru more of the low end in the original signal.
Please deadpan also test this method and see if you get good results. when you need a bit more low end, lower the mix knob and see if you get it back. Let me know.