If I could have only eyepieces, I would keep my 22mm and 35mm Panoptic. Though my 32mm Brandon and Zeiss Jena Orthos would be hard to part with ...
I've been comparing the 22T4 against the 22 Panoptic for the last 6 months or so. It has been on my mind for many years, but this thread was the last straw, so I picked up the Nagler.
After the last two nights of observing, I think the results are in re the 22 Panoptic vs. the 22 Nagler T4:
(the envelope please)
In my 4.7" f/8.5 Astro-Physics refractor the 22 Nagler has a slight edge. Both show a bit of field curvature, which could be my worsening accommodation. Possibly.
In my 16" f/7 Newtonian, the 22 Panoptic edges out ahead - it just seems to have a bit - ever so slightly more - contrast to it. Although it has less AFOV, stars at the edge seemed tighter. No field curvature at all, just a touch in the Nagler. The loss in true field is about 8 arc minutes - but I do have a couple of lower power eyepieces to fall back on if I need more field.
The deciding object was M27, the Dumbell Nebula. Both eyepieces presented the nebula as hanging in space, the edges seemed to have a hard definition. But what caught my eye was a chain of stars across the front of the nebula. Four noted in the Nagler, seven seen in the Panoptic. My friend George, Mr. 100 Degree AFOV and collector of ES100 eyepieces, actually liked the Panoptic better.
So in the end, the 22 Panoptic seems better in my primary scope, weighs less, and has no Instadjust. Add to this that 22T4 will fetch twice the price on the used market.
My 22T4 is officially surplus and on the disposal list - a some point. Maybe one more outing just to be sure ....