To close this one off, my preferred method is to create a simple wrapper for the Open() function. This probably also answers your original question about the scope of file handles too

Code:
Dim $fhLogFile, $fhOutFile
 
; Open log file... 
$fhLogFile=udfOpenFile("C:\temp\log.txt",5)
If @ERROR "CANNOT OPEN LOG FILE"+@CRLF Exit @ERROR EndIf
; Open out file
$fhOutFile=udfOpenFile("C:\temp\Out.txt",5)
If @ERROR "CANNOT OPEN OUT FILE"+@CRLF Exit @ERROR EndIf
  
Function udfOpenFile($sPath,Optional $iMode)
	If ""=$iMode $iMode=2 EndIf
	$udfOpenFile=FreeFileHandle()
	If @ERROR $udfOpenFile=0 Exit @ERROR EndIf
	If Open($udfOpenFile,$sPath,$iMode) $udfOpenFile=0 Exit @ERROR EndIf
	Exit @ERROR
EndFunction