I found that it cuts some of your mid to bass frequencies/tone regardless of where you set the tone control on the pedal. Its noticable when you strum a chord slowly with and without the pedal switched on.
I didn't like it with the distortion less than 12 o'clock but above that to my ears it sounded nice with plenty of added sustain without fizz.
Having said all that I'm using it with a Vox ADT50 (using AC30 model) to add more balls to some solo lines. I haven't tried it with my SLX yet cos I lent that to the other guitarist to use for a few weeks.
