Hmm, never had any issues with the Tokina 10-17, even here in Putrid Sound... ;-)
At f/4 the 16-35 isn't bad, but if I'm going to shoot at 16mm the Sigma FE or Nikon 16FE f2.8 is the lens of choice. Zoomed out to 35mm it becomes f5.6 and AF was very unreliable in Mexico, except near the surface is fairly bright conditions.
My experience, YMMV. I know a lot of guys love the lens, I just couldn't get it to work well zoomed out.
Which version of the 16-35mm are you using?
The present version is f/4 through the zoom range.