It's a nice idea, but the underexamined complexity is that most organisms on the planet have resting phases (seeds, spores, diapause states, dormancy), and these complicate the time issue substantially. Even more to the point, ectothermic organisms like plants have "environmental time" because metabolic rate is partially a function of temperature. This is where the "degree-day" concept used in agriculture comes from.
When I was a grad student learning this, we used to joke that a 1,500 year old redwood was older than a 4,000 year-old bristlecone pine. The reason was that the bristlecone was dormant for 9 months out of the year, and assuming that it didn't age while dormant, its "experiential lifetime" was actually 1,000 years of summers, whereas the redwood never went dormant, so its experiential and chronological ages were congruent. Overall, I'd be happy to see more work on the time dimension of organisms life-spans, and I'll be interested to see how the theorists incorporate environmental time into the equations.
