The taper switch on the EB is weird. Some people can tell a difference, some can't. Some days I could, and some I couldn't. As an expression pedal, the difference was miniscule. I couldn't hear it honestly.
The only thing I found to really help with getting it to work with the AFX was the slope control. I think Scott Peterson is the one that suggested the 12% thing, and that did it for me. The taper isn't perfect, but it is close enough to make me happy. I would rather deal with a less than perfect taper and have the feel of the EB pedal. I'm just so used to it I couldn't imagine using anything else for volume control.
D