Hi Programmer,
I used to own a 10" GSO scope. I found premium EPs made a HUGE difference! Not just for image quality but consequently it made observing so much more enjoyable. I have a Meade 14mm s4000 UWA which is an old copy of the Naglers. This EP is my favourite and made me want to observe more often. The difference compared to standard Plossls is massive in my opinion. I also think that the 14mm focal length is a great one for that scope (if you were only going to buy one Nagler).
One other thing... I could notice quite a difference in planetary detail between my Hyperion 8mm and my UWA 8.8. So I wouldn't necessarily class the Hyperions as premium. They are good, but in a fast scope they do deteriorate.
I don't think you would ever regret buying a Nagler.
Cheers,
Dave.