Ebb,

Very nice work!

You have the same system as I have... except;

I use an Atwood 750 for the small pump
I use a Rule 2000 (Gold) for the large pump
My buzzer is mounted up near the companionway (it is loud enough to hear in a hurricane... you can test it and hear it from the parking lot in the marina).

And (as usual)....

Your install is about 100x neater, cleaner, and more photogenic then my install.

For more discussion of this, and the thinking that lead me to the same system you have here see this thread.