I have to respectfully disagree with some of the first part of your post Alex. I have had, and tried the GSO Superview eyepiece and it was far worse off axis than the 38mm Orion Q70 I now own. I owned a 30mm GSO Superview for one night only and got rid of it the very next day because the off axis aberrations were so bad...and that was at F/5 !!! There *is* off axis astigmatism in the 38mm Q70, but it is a lot less than the GSO Superview. It also does not start at 25% out. Well, it doesn't in my 10" F/4.72 reflector. Aberrations in my 38mm Orion Q70 don't start until about 50-70% out. You probably tried it @ F/4 which is a big difference. I am on my second one, which should tell you something compared to what you said about the GSO Superview, lol.
I *do* agree that my eyepiece is better suited to a longer focal length telescope, but it does wonders on my 10" F/4.72 reflector as a finder EP and for viewing really big things like the Veil, M-45, and a few....and I mean *a few* deep sky objects, so I really see no point in spending a large amount of cash to star hop and view minimal targets.
The 38mm Q70 not black out on you and it is one of the easiest eyepieces to use eye-placement wise.
Another point I would like to add: If you want to spend heaps on a well corrected eyepiece, you could spend up to $300.00-$350.00 US on a used 35mm TeleVue Panoptic. I also tried one of those in my scope and stars are sharp to the edges. However, there is a trade off: Eye placement on it in a fast scope is extremely critical. I went back and forth between it and my 38mm Orion Q70 and in all honesty, the critical eye placement of the 35mm Pan drove me nuts and I liked my 38mm Q70 more believe it or not. I also owned a 34mm ES 68 degree eyepiece which basically works just like the 35mm Panoptic, but I sold that off because eye placement was critical as well.
I don't see a point in spending $300-$350 for an eyepiece that will only be used as a finder eyepiece for star hopping or in looking at a few targets like the Veil etc. I spent just over $100.00 Canadian for my 38mm Q70 and I had $200.00 left over to get more gear.
YMMV....
Cheers,