got around to posting it. Here's what I had to say:
I've been reading some reviews on Nikon's new 70-200mm f/4 lens with quite a bit of curiosity recently. Mostly, I've been wondering how well it will suit my needs, as the 70-300mm VR has not done very well for me, hand-held, and the 70-200mm f/2.8 is awfully expensive (yes, yes, why am I saying that when I shoot with a D4? Well, there are almost always limits).
Rockwell's preview (misnamed a review, since reading it reveals that he has not yet had one to actually use) says the extra stop shouldn't matter, as long as you're shooting digital. And I've seen similar comments elsewhere.
Well, one reason I'm fortunate (or, to put it another way, one reason I went with a Nikon when I wanted to get a new DSLR several years ago) is that my dad also shoots Nikon. And, happily, he has the 70-200 f/2.8 (VRI), so I was able to borrow it to get a feel for some things.
Bokeh? Yeah, that extra stop is noticeable, but not obtrusively. I certainly don't think anyone should be getting the faster lens for the bokeh. But the extra stop can make a difference. My daughter started gymnastics lately, and I was shooting her practicing.
I just couldn't get a good shot of her (moving; when she was pretty static, the shots were fine) with either of my longer lenses. Going back through the shots, I saw that I was getting 1/60th to 1/200th shutter speeds, even allowing the ISO to climb all the way to 12800. With that long a lens, and with her moving, that just wasn't working, even shooting off a gimbal. I think I should be able to get enough better with (lots of) practice to make it work off the gimbal, but handheld is definitely out. And carrying the tripod and gimbal is a serious pain (and infeasible when, as is usually the case, I need to watch my son).
Anyway, the point is, shooting with the 2.8 lens worked out just fine. I'm not sure where that leaves me, but at least I know a lot more. (Certainly, amazon currently offering 2% back with 24-month free financing on the VRII 2.8 lens is looking awfully tempting. If only I knew when the VRIII or VRIV model was coming out.)
So, after that testing, and with the deal mentioned (last December, I think), I ended up getting the newer 70-200mm f/2.8 lens. And I've been very happy with it, although 70-80% of the time, I think I'd be fine with the f/4 lens. Which, I guess, is my way of saying that you should be fine with either lens unless you're shooting moving targets in less-than-full lighting.