And I have told this story elsewhere, but it kind of bears repeating. I had read many posts over the years that suggested that Comet Catchers were typically undercorrected. What one needs to remember though is that the Comet Catcher is f/3.6 and at that speed most eyepieces are no longer diffraction limited, and if you use them to test for SA, the SA of the eyepiece itself can be greater than the SA of the system you are testing in.
Now the NV gear at prime focus has a flat photocathode so this induces no SA at all when the objective is removed and the device is used in the eyepiece.
When I star tested with a Plossl, it was easy to see that the secondary shadow size was different inside vs outside of focus. When I did it with the NV device though and using a mangifying glass at the NV device eyepiece, I found that the shadows were very close on either side of focus.
Now no one would buy this as a planetary scope and for low power sweeping, SA is simply not all that big a deal, but the point is that I feel as if the optics got a bad reputation when it is more likely that the optics are diffraction limited, but many eyepieces are not diffraction limited at f/3.6.
I think they are super fun little scopes though, and I would rather have one of these than an 80mm achromat. Goes much deeper, and field is better off axis because it is flatter and sharper. A 16mm Nagler would probably be amazing in a Comet Catcher, but I never had one to try out.
Fun little scopes though, and if you are thinking about NV, it is a top choice for a small sweeper and lap scope. I think there are at least four of us that had our first Horeshead view ever using a Comet Catcher and NV.