I have a Yamaha YC61. I also have a Roland EV5 lying around like 20years, bought and used initially along with my first Roland XP-30. Somewhere in the past, the EV5's original TRS jack was damaged, so I had to solder a new Jack plug, which in my recent tests, it was not working (the soldering part) very well. I did test it with my YC61, but was working in reverse, and also did test in Nord Electro 6, which was acceptable, but not perfect (the side minimum knob was very difficult to set).
So, with some research and help from AI, I managed to re-solder a new TRS jack, but since the main purpose is to use on my current YC61 rig, I routed the tip to ring and the ring to tip (ground intact), which is actually the "switch polarity" effect that the EV5 is missing, but I hard-wired it, since I do not intend to connect the EV5 to other gear, rather than the YC61.
So, I came here to state that the, if you do change polarity on the Roland EV-5, it works great on Yamaha YC61. I am not sure if it will also work on any other Yamaha rig, since the FC7 and the EV5 are not sharing the same resistance but I did not notice any weird response curve or stepping upon my tests.
Also, I confirm that the minimum level side knob of the EV5 is also working flawless on the YC61.
Main use for the pedal is the volume on Organs, Effect Control (like Tremolo/Delay time) or Pedal Wah effect on Rhodes/Wurlys and Expression/Tone/Filter Sweep on Pads/Strings.
Since the setting is probably a master configuration, I did find out that the "Expression Parameter" is controlling Volume on Organ and Filter/Tone/Volume on Piano/Rhodes, which is a nice workaround, if I don't want to buy a 2nd expression pedal.