Lower voltage makes voltage drop across the line proportionally worse. Depending on the purpose PoE is probably the way to go since the wiring and hardware is all standardized and safety certified.

Unless you mean running AC and installing inverters in the wall? What is this even for? All my electronics are DC but critically they all require different voltages. The only thing I might benefit from would be higher voltage service because there are times that 15 A at 120 V doesn't cut it.