Definitely a step in the right direction. I don't know what took so long. However:
- The measurements are incomplete: he published graphs but not numbers.
- He didn't measure the Tera Player when loaded. With 10Ω and 20Ω output impedance, you can be certain that the Tera Player won't play well with a number of cans. Measurements that would get affected the most are frequency response and stereo crosstalk.
- Like he says himself, there is something wrong with his iPod Touch measurements.
You can almost be certain that no one single player plays well with all cans, is there any?