[Don Pensack]

Their design was penned about 5 years ago, so not a copy of the Delos.
Also, radically different glass types.
Eye relief is different in every focal length.
Focal lengths: 17.5, 14, 12.5, 9, 6.5, 4.5mm
These are designed to yield no vignetting down to f/4.
[note: that doesn't mean no induced astigmatism or other problems. They still need field review from experienced users.
I've see a perfect eyepiece with unfortunate Edge of Field Brightening, so you never know.....]
Any intelligent mfr makes the focal planes as flat as possible to work in as many scopes as possible.
An eyepiece is more likely to encounter a strongly curved focal plane in a refractor than in a dobsonian, but an eyepiece designed for one wouldn't work well for both. That's why more eyepieces are fairly flat.
Some expensive eyepieces, though, do not have flat fields, so it shows that the pairing of eyepiece and telescope really is determinative of optical results. A classic example is the Pentax XW, in which the four short focal lengths have a negative field curvature and the 4 longest focal lengths a positive field curvature. That most complaints about the longer focal lengths come from newtonian users isn't surprising. That the 4 shortest focal lengths get great reviews by the same scope users also isn't surprising.
Alex is right to suggest a little more info would be useful.
Since such info would impact sales, I won't hold my breath, though.