Nearly everyone who's used one for a while has a volume pedal horror story. Broken string. Scratchy pot. Not transparent. Whatever. I'd been looking for an affordable optical pedal for a while. Morley came through, and it's a fun color to boot. (Seriously green, y'all.)
I haven't run any objective tests, but to my ears, the 20/20 Volume Plus is very transparent. The taper is a bit odd for me- lots of control for the quiet end, less for the loud. Since I tend not use the quiet end as much, I set the minimum volume where I wanted it, and just switch that off if I want to go quieter. Using the minimum volume helps with my biggest complaint; I wish the pedal had more throw. It's not like Morley is alone in this, but some of us with less foot coordination would like more travel!
The pedal's width surprised me at first, but hey; they have to put the controls somewhere.
Finally, assuming light exposure ahead of time, the logs glow in the dark.