The Radians all have a very long 20mm of eye relief and a fairly wide eye lens and they all are very comfortable/easy to observe with. However,some users do not care for their click stop eyeguards.
The newer high power Type 6 Naglers are also a big improvement (with respect to eye relief and the size of their eye lens over the older 4.8mm Type 1 Nagler). I just got the 2.5mm, 3.5mm & 5mm Type 6 Naglers and I'm very pleased with them.
I do not have any experience using any of the higher power Pentax eyepieces.
The newer high power Type 6 Naglers are also a big improvement (with respect to eye relief and the size of their eye lens over the older 4.8mm Type 1 Nagler). I just got the 2.5mm, 3.5mm & 5mm Type 6 Naglers and I'm very pleased with them.
I do not have any experience using any of the higher power Pentax eyepieces.