Not true; there is a difference when it comes to error handling. If you
omit the "WorksheetFunction", you can trap the error in a Variant and test
that with IsError. If you include "WorksheetFunction", you must trap a
run-time error with an On Error statement.

Sub AAA()
Dim V As Variant
V = Application.Sum(Range("A1:A3"))
If IsError(V) = True Then
Debug.Print "ERROR USING SUM"
Else
Debug.Print CStr(V)
End If

On Error Resume Next
Err.Clear
V = Application.WorksheetFunction.Sum(Range("A1:A3"))
If Err.Number < 0 Then
Debug.Print "ERROR USING SUM"
Else
Debug.Print CStr(V)
End If
End Sub

Thanks Chip. BTW, the newsletters are very educational.
-pb