Here is what I do (or don't do):
I have seen enough disparity in professional grading to realize I will not send my raw books in to be graded. 9.0's that look like 6.0's. 6.0's that look like 9.4's. Nah. Not for me. Too ambiguous. Can you say "Toploader"? I can. My collection is mine to do with what I please. So, I could bring a book to a signing, have it signed and know that I was there and the person signing it was actually the person signing it.
If I had - say - a raw Batman #2 and it was in really nice shape, then yes. It's valuable, it's "rare" and I want it protected so the book can be "retired". I would deal with the assigned grade.
If I have a fantastic looking raw book, why am I going to bring it to CGC or CBCS and chance have it come back as a lousy grade when I know that my grade is more or less accurate and I'm happy with the book? If a grader had a fight with his/her boyfriend/girlfriend/cuckold the night before and he/she didn't get his/her britches tickled, I don't want him/her taking out their problems on my book.
I could post example after example of grading disparity via scans. And NO. I can't see the grader notes but I encourage you to use Green Lantern #76 as your example. Those things are all over the map. The only ones that look accurate are the 9.6's.
Further, if I have a 9.8 graded book I purchased, I am not going to chance having the grade jiggered by a signer who damages it or the grader damages it. In my view, it went in and was graded under the same, assumed "uniform" criteria and got a 9.8. It comes back under the same, assumed "uniform" criteria a 9.4 or 9.6, that means someone wasn't careful and expects me to deal with it when the reality is someone damaged my book. If I need a specific issue signed, I will buy a second high grade raw and be satisfied with the signature and the grade.
OR. I will bring a graded 9.8 to a show and have the artist/writer signed the case and photo them doing it with the serial number well in view in case I want to sell the thing at some later date. But it isn't coming out of the holder.