I mostly moved to Sony but kept my 500 pf and my D500, it is in my car wherever I go. I love the portability, the way it handles and on the d500, 750 focal length. Just sold my 600 f4 G, loved it but it is heavy and the 2 piece hood was a pain. The sony 600 is lighter, and much easier to shoot even without a tripod, it just seems to balance nicer that my Nikon 600 f4 G. If I am stationary the 600 on the tripod and the 500 pf/d500 hanging from a strap, on a hike the 500pf is just so easy to walk with. You know your going to buy both anyway so treat yourself or the 800. As to cost, yes very expensive, and think how well these Lenses holds their value. With quality glass you can sell them without taking a huge hit much less than if you rented one. I tell my bride that they are on a long term loan but being used every day!