...why do you want the option to disable 3-phase transmissions? Is having it harmful for the majority with split phase?
It wastes power.
True, but only when transmitting, which for most people is a very, very small percentage of the time, so I don't see the overall power consumption of the unit being significantly affected by it.
For example. A typical command takes 2 seconds to transmit, so even if the WM100 transmits 100 commands in a day, that is 200 seconds of 86400 or 0.23% of the day.