Quick Poll: Pentax 20mm XW vs. Radian 18mm

Background Info:
I have an 8" f/5 high-end reflector
I'd like a moderately widefield EP with an 1.25" barrel.

Pentax 20mm XW gets me 51x, 70 deg. FOV.
TV Radian gets me 56x, 60 deg. FOV.
Eye relief is essentially the same (and I need the eye relief).
Radian is about $70 less.
Weight and build quality OK with me for both.

I've read some less-than-glowing reviews on the 20mm XW. Not sure what to do. I want to use an O-III and UHC with it.

Please vote: given the above, go with the Radian or the Pentax?

Thanks very much for your opinions!
Doug

I'd vote for the 18mm Radian between the two, but it only has about 75% of the TFoV of the Pentax, so these eyepieces don't quite seem interchangeable. It's the field curvature of these longer 1.25" Pentax's that puts me off in my 10" f/5 Newt. The 18mm Radian, IIRC, is flat and sharp to the edge.
--
Mike