I know Jim Schmidt sells what seem to be really nice Carillo rods and you can also buy conventional Carillo rods from other folks, and a lot of racers use them.
I've had material sciences classes and from them I know that Aluminum doesn't have an endurance limit, like steel does. That is, if you plot the level of applied stress on the vertical axis and the number of times to failure on the horizontal axis. You'll see that the graph starts out near vertical and becomes more and more horizontal as you reduce the stress.
For steel, the line eventually does become horizontal, which means that if you keep the level of stress below a certain limit, it will last forever. For aluminum, the graph never becomes horizontal. It flattens out quite a bit, but it keeps going down, which means that eventually an aluminum part will fail.
What I'm wondering is though, how common is it for high mileage aluminum rods to fail in street use, without a big-end lubrication failure? Our British vertical twins came with aluminum rods from the factory, but outside of this application, they're generally considered super trick, short lived parts. I think that the only other folks who use aluminum rods are some drag racers, since they're the lightest thing out there.
I know there are folks who've run Commandos over 100,000 miles with stock rods, but I was just thinking about this as my bike is getting close to 100,000 miles on it's stock rods.