After plowing through three B&H sales reps in an hour and a half, Josh and I came to find that it's all down to preference. Some said that the 70-200 2.8 VR
blows the 8-4 out of the water (which is not hard to believe), but others were firm in their belief that the 80-400 reigned supreme in the 201+mm range.
The range is perhaps the most important, at least when spotting at JFK
It was recommended that Josh rent (or perhaps borrow) both the 80-400 and 70-200 and conduct a comprehensive study about how they behave and whether or not they accomplish what he would like.
From what I gathered, though, despite the lightening fast AF
the 2.8 offers, the 80-400 may be the more versatile and practical
lens at the moment.
I also gather that the 70-200 f2.8 VR
with a 2x teleconverter is out of the question.
However, I think that the idea of renting the lenses to conduct a comparison is a good idea--the sales rep made a good point in saying that, "when you're going to spend thousands on a lens, you should know that it's what you want. Don't be the guy that comes back to return a 70-300 he bought for a birthday party. Spend the few hundred to rent, so you're comfortable."
Quality wise, the 70-200 f2.8 VR
may work if Josh starts shooting large .jpg, allowing more room to crop shots that would normally require a 400mm zoom. I think that would work.
I think I'll...uh...I mean...he'll
love whatever is decided on.