Thanks for the link. That was informative. Marco has a different purpose in mind: he'd like to get the world to do a little more exercise and get a little fitter, and that's admirable. Accordingly, he's sort of wedded to widely available technology like cell phones and HRMs.

We spent a lot of time looking for correlates of watts/HR back in the day, but in the end I figured since I had a power meter, I wasn't that concerned about watts/HR; rather, I was more concerned about watts/kg or watts/m^2 of CdA.