At my job, I've been cleared to buy a 70-200/2.8 VR II as part of an upgrade to a D810, 14-24 and 24-70. I have to do a good big of walking and most of my photography is at construction sites and scenics of roads and landscapes. I'm trying to get the most bang for the buck and questioning the need for the F2.8, when the F4 model is a bit lighter and as sharp or sharper than the 2.8. I know the 2.8 is a killer lens but I'm not sure I really need it. I had a d200 with an 18-70 and a D300 with an 18-200vrII, now the d300 is backup, thank goodness. Has anyone used both of these?

Do you do any night or low light shooting?
If so I would go with the 2.8.

This.  I have the F4 model and love the lens.  I seriously considered the 2.8 but I hasn't been a big issue.

 

If your job does not include shooting sports or portraits, then you probably do not need the f/2.8.  Even with the f/4, your description suggests your are shooting at f/8 or smaller any way.

In this case, I would go with the smaller and lighter f/4 version, a killer lens at a much smaller price point.

I said "eff it" and got the 2.8. This lens will be used for a good long while and I expect the 2.8 to be mechanically superior to the f4 for a very long life. I've been at the job about 5 weeks, so they must be happy with my work so far to let me go spend that kind of coin.

There's a reason it's one of the Holy Trinities !

I love that glass.

Let me say, the d810 with the 70-200/2.8 produces some incredible images. I shot a controlled burn today, I marveled at the details produced, and I used a d800 at my last job.