I don't have much experience with two boat training. I could see where it would have great benefit and more than using a GPS alone.

But I'm lucky to get to 6 races a year. Two boat training would indeed be a luxury. I do get a some weekends to sail alone and believe that reviewing these metrics - even delayed - has been invaluable to my learning curve. It's ten times more enlightening when you review multi boat performance using Kattack and the summary statistics it provides. Do some additional manual analysis and you really get the picture.

I believe with the advent of the GPS, sailing will have statistics similar to baseball. I'll bet the AC45 teams study these metrics constantly and work on performance issues they discover.