I didn't realise the XP-Gs were that efficient though I'd guess that was at a much lower drive current than 1.4A - they usually seem to measure the efficiency at 350mA or less. Not that I'll ever know as you'd need to spend tens of thousands on lab gear to test this properly. I seem to remember around 80-90 lumens/watt when hard driven but my memory may well be at fault like when trying to remember which Cree LEDs have the ring.