So I guess my scope is coming with a 30mm erfle and 9mm Plossl. Do I get a much better 30mm or 40mm like the ES82 and then a a good medium and higher power or should I just use the erfle as my finder for now and get 3 good wife field eyepieces that are medium and high power. If I replace the erfle I’m thinking I’d get 30mm, 12 or 10mm, and 8 or 6mm. Or if I use the erfle as a finder piece I could get something in the 22-17mm range with maybe 12 and 8. I’m a beginner so I have no idea what the erfle will be like. Looking at ES82, Baader Morpheus, televue Nagler, and Delos for all EPs
My 2 cents:
The short story:
For now, I would keep the 30mm GSO SuperView as you finder and use your money to invest in good quality, shorter focal length eyepieces.
The long story:
I love to star hop and over the years I have built up a set of some very nice eyepieces. My low power "finder" eyepieces are the 41mm and 35mm Panoptics, the 31mm Nagler and the 21mm Ethos. These are as good as it gets.
About 2 months ago, I bought a used 30mm GSO SuperView. I really had two reasons. First, I like to keep myself grounded, keep in mind that one does not need optically perfect views in order to enjoy the night sky. The second reason was to remind myself exactly what this eyepiece is so I could help people such as yourself. I'd had one before for much the same reasons but in 10 years, memories weaken.
I have been using the 30mm GSO Superview as my primary low power finder, wide field viewing eyepiece for about 15 nights, a few under dark skies with my 16 and 22 inch scopes but most in the backyard with various scopes including several with my 10 inch GSO Dob, it's the 2002 version of the Skyline Dob you are getting. (It's been a very good scope for me)
As a finder, the Superview makes a good finder. The field is wide and the center is reasonably sharp, near the edge, not so much. There is no field stop so estimating the true field of view is not so easy but I measured the AFoV at about 65 degrees which translates to a 1.6 degree TFoV, plenty wide for star hopping.
For use as a finder, I thought I would be giving up quite a bit compared to the 31mm Nagler because of the off-axis sharpness but I really wasn't giving up too much. The field of view is narrower but the Superview is still generous by my standards. Some tiny, faint fuzzies at the edge might be missed but this seems less of a concern than I remember.
Optically, it is some sort of a modified Erfle or some such and the stars at the edge of the field are definitely not pinpoint sharp, far from it. This is primarily an aesthetic issue, sharp stars at the edge are an expensive proposition. To achieve the ultimate sharpness in F/5 Dob, there's the coma corrector, the fancy eyepieces.. The 31mm Nagler and the Paracorr 2, I have that and it's essentially perfect but it's also over $1000 and weighs over 3 pounds..
But one does not have to have aesthetically perfect views to enjoy the night sky. In my mind, this is essentially an attitude question. With a cup half full attitude, even for a picky old codger like me, the 30mm GSO SuperView provides enjoyable views, despite the imperfections.
For a beginner, it'll take a while before such imperfections become bothersome, they may never, you are too busy, too awestruck, by the wonders you are seeing in the eyepiece. There may come a time when you want to invest in a better quality finder, low power eyepiece but in my mind, you would gain more by investing in shorter focal length eyepieces because that is where you will be doing most of your more critical observing.
Exactly which focal lengths I would recommend, hard to say, eventually you will want more than 2 or 3.