I don't think normal soldiers will be suffering from old age. I mean, most humans are recruited as 20-somethings, at most, and can live to at least 40 years old before they would be considered old. 240 turns for a 10 gp investment sounds pretty decent, for me...
Older units, like Crones of Avalon, might start suffering faster. And Triarii of Pythium, and maybe Principes, etc old and experienced soldiers. Even in their case it probably won't be as bad as it currently is with Principes (sometimes they have a random affliction), because aging is supposed to take time.
I'd also like to see the new Burden of Time in action!
