Having tried voice announcement, and not using it anymore, take my advice: Use it sparingly. Keep your voice files as short and simple as possible. "One" is tolerable, "Channel one" gets very annoying very quickly. You'll have to hear that file EVERY TIME you switch to that channel. It WILL get repetitive. It's a cool feature...for 30 seconds. After that it's an irritant.
If you're actually forced to change channels when not looking at the radio, the VA feature is practical. Otherwise I'd just skip it.