Go the Pentax. Mine is awesome in my F5.
Excellent sharpness and contrast, eye relief is perfect, (sometimes ER is overlooked when deciding on an EP) very very comfortable. After hours of use this EP will not stress your eye, and the eye cup is adjustable (twist up and down to adjust eye postion). I would choose ER over field of view any day. Build quality is amazing.
You will only see MINOR softness/streaking stars (coma) at the very edge of field at F5, only the outer 5% or so of field, this is mostly due to my mirror (most people would not notice it, I'm fussy which is why I went for the 30XW, didn't want to fork out for a Paracorr). Very well corrected EP, and no distorsion. In my F7 the EOF is perfect.
IMO, can't find a better low mag wide field EP.....
