One feature I like on my separate hailer/automatic fog signal is the
ability to listen through the speaker. The speaker is up and away
from the sea and sail/engine noise, it is unobstructed if you're
hiding behind the dodger (or in my case pilot house) and it's
amplified. I don't know if the combined units can listen and if they
can listen if they can do so while monitoring the radio... Still, if
I were to do it again I'd get a combined unit and have two installed
vhf's.

-- Tom.