Hi Eternal.
To put it in simple terms, I have a GS 12" Reflector. I have been using series 500 El-Crappo EP's and fairly reasonable GSO EP's and have been happy with the views (well, maybe not happy with the Series 500's).
I am very happy and suprised at the quality of the GSO mirrors! They aren't 'Mark Suchting's or Observatory Grade 'Ritchie Cretian's, but they are fantastic for a mass produced item. Very rarely does anyone complain about the views using GSO mirrors.
I thought I was getting very good views with the EP's I had, but I was presented at Camp last year with a Pentax XW7. WOW!!!!!
Now I know the optics of my GS 12" are great! The premium EP shows just how good these mirrors actually are. I have also had all sorts of Premium EP's in my scope at this years camp and all were fantastic. The EP on it's own can't improve a bad mirror, so the mirror must be good. Feel safe buying a GS mirror.
Just my 87.5 cents worth
