I'd beg to differ, Eric
!
You cannot see the whole field in anything over 70degrees without moving your head around. This may be ok for some people, but not everyone.
My own opinion, & that is what is being asked, I think ultra wide fields are over rated - our human eyes can't see the whole field at once.
I've tried a variety of these, from cheapies to Naglers, Ethos & ES 100's (thanks Eric
). The image quality of these ranged from ok to bloody amazing (Eric's ES 14mm 100), but that I had to move my head around, & that they all have problems with critical eye positioning, takes away for me my consideration of them to be in my kit.
To say that an object stays in the FOV for longer is miss leading, as you need to constantly chase down the object every time you pull your head away. In EPs with upto 70degrees, the object just is or isn't in the FOV so there is no double guessing.
Consider the Vixen LVW's or the TV Delos range if you want to spend the big ones. The ES 68's are great too, but shorter eye relief & only go down to 16mm in focal length. The Hyperions are good too, but maybe not all models are in the same league as the LVW's or Delos.