That's interesting, i only know the 1000lbs figure for the low fuel warning as well, and none of our NGs flies ETOPS nor do we plan to fly ETOPS with them. But lowest i had for total reserve fuel so far was 1.900 kg and that was for a diversion from TXL to SXF (just a short hop over berlin). We expect to get a low fuel warning though when we have to use diversion fuel, final reserve is usually way below the low fuel warning threshold.