I've had the 80-400VR for 1 1/2 yr now. It has survived Tokyo's cool wet winters and hot humid summers, not to mention the pollution. That lens has made several trips with me to Hawaii, hiking around the interior of Oahu, and roaming its beaches. Many of those flights were made on military transports, not known for comfort and padding. It's also made a long round trip from here to Texas, Oklahoma, New Mexico, Arizona, Texas again, and back to Tokyo. That one was last summer, and the lens was well used every step of the way. And with the exception of my last trip to Hawaii after 9-11, the 80-400VR, and all my other equipment, was always carried on board in my Outpack backpack. After 9-11 was the first trip I ever used a hard case, just in case I had to check it.
The point is, as long as you take care of it, clean it, etc., this lens is durable.