Here is what I ended up with for reference. It seems view.focusCell(..) calls ensureVisible() as well.

Code:
success: function(xhr) {
    var jsonResponse = Ext.decode(xhr.responseText);
    var row = Number(jsonResponse.data); // simple numeric value
    var offset = (livegrid.view.visibleRows / 2);
    if (row < livegrid.view.lastIndex) {
        offset = 0; // going back up, top of grid
    }
    livegrid.getSelectionModel().selectRow(row);
    livegrid.view.focusCell(row+offset,0,true);
}
Regards,
Scott.