From what I hear there is a way to enable Front Panel Programming (like the XTS), but I don't know how...
To answer your question, the hardware in the radio can only go so low... It seems like 430 is the limit. If you try and force it, you could muck up the radio (i.e. opening the synthesizer lock) and turn it into a brick...
The F40 is a great radio - built like a brick and can do almost anything... You won't regret buying it, I have two and they are my favorite.
