Try not to start a rotary vs v8 argument. I actually dont hate the rotarys just the reputation. You see the small blocks have a tendency to go the extra mile.
If I were admin, I would just lock this thread that came back from the dead. But since I am not an admin, I will just post.
Given similar circumstances, I argue that triangles and pistons will last approximately the same amount of time. If you have a naturally aspirated engine, they will both go 100K+ miles easily. If you twin turbo both of them, their life will be shortened. If you toss a single turbo and run a huge amount of boost, life is shortened as well.
~James