ChrisJ, this seems to work for me. I built the command like this instead.
 Code:
    $sqlcommand = '%COMSPEC% /c'
	  +' C:\Development\mysql'
	  +' --host="$dbhost"'
	  +' --database="$dbname"'
	  +' --user="$dbuser"'
	  +' --password="$dbpassword"'
	  +' < $SQLfile'
	  ;+' >nul 2>nul'
    ? "echo out command here"
    ? $sqlcommand
    Shell $sqlcommand