I bought a Mustang IV from Andertons earlier in the year and I was using a mono volume pedal until the pedal died recently. The replacement solution was a stereo volume pedal and the Boss FV-500L does the job perfectly. It is very responsive and has a friction setting so you can create any sort of feel you want from light to heavy. There is also a master control knob for setting the Maximum or Minimum volume of the pedal. An output jack for using an external tuner is also included.
For those like me that can't work without a foot volume control this is the answer.