....Anyway, I am pretty familiar with aging of wire rigging (roughly every 10 years), but what is the life expectancy of rod rigging?.....
This much is clear. No one agrees on the answer to this question.
I was looking at a boat with rod rigging, so did some broad research. First, I spoke with the major supplier of rod components, NavTec, at the Annapolis Boat show, who said inspection at 6 years and replace at 10 years.
Most rigging vendors have said, dye penetrant inspect every 6 years and replace on condition. Some say replace on a life limit of 12-20 years. The inspection was the only standard answer.
The mushroom heads at the end of the rigging will fail first, in most cases. The advantage of rod rigging is the head can be cut off and a new one formed. As long as the turnbuckle is long enough, you're back in business. You can also get longer screws for the turnbuckle.
If there is any cause for all the confusion or different answers, it's possible that one's use of their boat and the relative sizing of the rigging is a variable. The lightest possible size, coupled to a racing boat that pushes stresses and puts extraordinary miles on the hull, is going to need time limited replacement long before the weekend warrior.
I still have wire rigging and generally pull the stick every 5 years. I always pay the local rigger to do an inspection and write a report for me. It's pretty cheap and I think their eye is better than mine.
p.s. my wire rigging is now 15 years old. I had it inspected two years ago, with no failures. I expect to get several more years out of it.