I have had both of these eyepieces and preferred the Pentax, Larger FOV and longer ER more suitable for myself with nice contrast and neutral stars a very nice ep but alas still not enough FOV for myself so parted with it.....
The XF 8.5mm is very sharp and lightweight. It's been suggested/confirmed that it doesn't have the very best coatings like the more expensive XW line. My own experience was that there's a little bit of reflection from bright objects like planets but I still regard it as an excellent eyepiece. Eye relief is 18mm from memory.
