the 150-500 performed for me very well, was a great lens for the money, had some great shots with this on my D300, one of the best that i had for taking shots of swifts
because you could push and pull the zoom in very quick, the 150-600 is a much newer lens that i was also pleased with, the only gripe i would have with the 150-500,
is its very noisy on the vr..