To the point, the anaerobic threshold of the runner should be evaluated, under ideal conditions via a portable diagnostic tool that would allow the test to be conducted via running on the actual track. This would ensure that the biodynamic conditions of the test are accurate.
Short of this I think the Omega Wave test is probably the most favorable alternative because the in vitro treadmill test, while it dynamically for all intents and purposes running, is dissimilar due to the mechanized propulsion.
Also ideal, yet not yet possible to my understanding, would be real time blood lactate measurement. I think this is only possible in vitro as of current.
So while generalizations can be made regarding the bioenergetic demand of the various events, the more important issue is the specific biological power of the athlete which then provides context to the energetic demand of the event for that athlete specfiically.
Even a perfect test would only give you a perfect picture of how energy systems divide up now- not how it would look at a higher performance level- so attempts to apportion work according to the current picture are doomed in the long run.