my experience is just the opposite...have had 3 8.0 or higher pgx books, come back 1 full grade, 1/2 grade and 1 1/2 grades lower when cgc'd (and one had tear seal missed by pgx , but the glue was minor enough still got blue label)
..damn GAtor,that really sucks..and i asume they were golden age books,with that glue comment.ive heard bad things about pgx golden-age grades,but the opposite about silver-age... my experiences are all in the possitive im 6 for 6 on the + side over the last year or so...
pgx 8.0..pressed came back 9.4 WHITE (batman 227)
pgx 8.5 straight sub.. cgc 9.2 (asm #50)
pgx 8.0 press.. cgc 8.5 (hulk 102)
pgx 7.0 straight sub cgc 8.0 white ( ff #48)
and two AVENGERS 57's last year:
pgx 8.0 press came back cgc 9.0
pgx 9.2 straight sub cgc 9.4
but im afraid im due for a donkey one of these times....
I had a similar experience back in 2006 when I bought a small late 60s early 70s OO hoard (multiples of DD #40 - 70, Iron Man #1-35, Silver Sufer runs, Conan #1-5, Subby #1-40, Captain Savage #1-last issue) from a local collector. He had sent in a bunch of books to PGX, but since I bought the books in November I subbed 60 more books to PGX (graded out between 9.2 - 9.6 with a few 9.8s) in order to catch the post X-Mas run on eBay. I finally resubbed the remaing PGX books with CGC and sent in the "undercopies" that were not good enough for 9.4 IMHO. The PGX 9.0/9.2 books all came back as CGC 9.4/9.6, and the 9.4 PGX books came back as 9.6/9.8 from CGC. The raw books that I sent in came back 9.4 - 9.8 from CGC.
The worst part of it IMHO is that I was debating whether I should resub the PGX 9.2 and 9.4 Conan #1, 9.2 Subby #8s, and 9.2/9.4 Silver Surfer issues that I bought from him. They looked way better IMHO.