how easy would it be to add an extra bit of logic to get_records.php that allowed an extra variable to be sent in the URL get request.
I was think something like the first letter of the account name therefore splitting the number of records (sort of into 26)
I dont know PHP (at all) but it seems that in get_records.php :-
if (isset($_REQUEST['last_sync_date'])) {
$last_sync_date = $_REQUEST['last_sync_date'];
$crits = array('>=:Edited_on'=>$_REQUEST['last_sync_date']);
} else {
$last_sync_date = false;
$crits = array(); <--- THIS BIT COULD BE USED FOR THAT PURPOSE ?