It sounded like ETNZ had some problem with the traveller in the ETNZ vs AM race, which may explain the speed dips in some of the turns.
It would be very interesting to see a VMG plot similar to the boat speed plot above. It would help to determine which tacking approach is preferred - point low and fast out of a tack then head up vs come out of a tack high and slow then build speed. I suspect the differing tacking approaches we see between AM and LR/ETNZ may, in part, be determined in part by the camber depth potential of the main - the boom systems seem flatter down low and may not be as powerful at lower speeds. I have also been wondering whether a flatter main may explain AM's speed edge downwind.