Full frame: Tokina 11-16 vs 16-35 II @ 16mm f/2.8

I went through the same thing you did when I went from crop to FF. The Tokina was my favourite lens in my bag and I thought I could still use it at 16mm on a 5Dii. While it technically did work, the corners were heavily vignetted at f2/8, and this got much worse with any sort of filter attached.

I was devestated to sell it but there was really no sense keeping it. I bought the 17-40 f4L to replace it and it is nowhere near as good as the Tokina was, but still much better on FF. I am now looking at selling the 17-40 and go for either the Tokina 16-28 f2.8 or the Sigma 12-24.