to summarize, what you said jack, is your stats are too complex to show rebills, and instead we should look at what each free member is worth.
What I am saying is that your proposed "long term value" is just some smoke and mirrors, and doesn't tell enough. your stats aren't that complex, and you can simply solve your complex stats issue with this simple stat table in the WM section:
uniques - free trials/$ - newsales/$ - upsales/$ - rebills/$
THIS IS SO SIMPLE!! don't make it sound more complex than it has to be!!