Not sure about the H version, but I used the L version fine.

I did use a splitter box when I had three factors… It technically worked… But was not very practical to be honest as it controlled too much that just seemed to make things a mess… I suppose I could have spent more time switching off the factors I did not want to control…. But it go kinda complicated.

Another way to do it is control the first factor with a single lead then control the others with MIDI.

For me, in the end I opted for a mission expression pedal that has 2 channels, you change channels with a toe press… Down side is you can only control 2 units and only one at a time… Unless you use the midi option.