I feel for you. I recently had a PGX 9.4 come back as a CGC 8.0.
That cover is really fantastic! I feel your pain. I sent off a PGX unrestored 5.0 and it came back with restoration. The restoration is minor and I love the book but...
Lesson learned on buying PGX
I've managed to dodge that bullet but the PGX books I submit consistently come back with lower grades, even for books in the 3.0 to 4.0 range. Occasionally, the book comes back with the same grade. Not a huge sample here -- easily 20 books, though -- but pretty consistent results. Typically the pq ends up worse as well. None of the books came back with a higher grade and none with better pq.
CGC goes thru every page and spends time finding little things that add up IMO. Thus the lower grade. I have seen a lot of PGX books and some CBCS books and the both grade a little higher than CGC. I think that after 70 years you have to grade a little lose by not picking book apart for small things. I have seen CGC grade a Batman 2 5.0 or 5.5 that my buddy thought should be 6.0 and he sent it back and it got a 3.5 i saw this myself. Joey has a Sup 2 that looks better than my 6.0 and it got 4.5 so all the gradeing people get things wrong just my O.