The Sparkle Drive is a very versatile drive pedal, offering everything from clean boost to full on dirty Tube Screamer tones. The Clean blend allows you to layer both clean and dirty sounds (kind of like playing through two amps, one clean and the other dirty). One of these has lived on my pedal board for the last 4 years and it sounds great for both guitar and bass.
A common mod to this circuit is adding some clipping options. On the PCB I’ve added 2 extra pads right above the “Gain 2, Gain 3” pads. These will allow you to use an on/off/on DPDT switch to go between which ever diode combination you want. The most common combination seems to be the stock 1N4148s and red LEDs. The center “off” position of the switch will remove the diodes altogether. See lvlark’s vero layout for the switch diagram.