What I know of AC electricity, frequency is very important. Electrical devices are built for the frequency where they are sold. A device built for 60HZ will not work properly on 50HZ. Electric clocks will run slow, for example and motors would overheat. Airline travelers who fly frequently buy converters for use in countries where frequency and voltage is different from US/Canadian standard. The electric shaver built for US/Canadian use won't work in London or Paris without a converter.
Question for the user base here: Have X10 modules been affected during "brownouts, where voltage is reduced? I live in Baltimore, where brownouts are very rare.