Two LFOs - because it is awesome! About to box up a dual LFO Escobedo pwm. Square waves adding and subtracting, making a city skyline waveform, then softened with a series cap and a cap to ground. I used an op amp stage to mix the two LFOs, which would complicate your switch. How about mixing the two thru the - input of an op amp, and using depth controls on each LFO - controls that can take one down to zero?
Once I heard my two LFOs blended into the pwm, I realized I would never turn them off. Matter of fact, in a knob-reduction exercise, I put the depth and speed controls inside. I don't expect to ever change them frankly. It's wild.
The uglyface is a similar sounding extreme device - crazy, really. This is not a fuzz& chorus. You may find that adjusting the LFO speed is like... Deciding which sunglasses the bikini model wears. Gotta have em, but do the subtleties matter?