I sent in 4 cracked out slabs (all 9.8's) for a Romita signing. None came back 9.8. This is no fault of the facilitator or any rough handling of the books.
That is one hell of a risk to take. I persuaded one collector who had a Bats #227 graded as a 9.6 to leave it as it is, even though he wanted to crack it out and have Adams sign it, just in case it came back a lower grade and that was a 9.6. To de-slab a 9.8 in order for Romita to sign it is far too risky. I take it from your post that that didnt even all come back a 9.6 so you have to ask yourself whats better a 9.8 or a lower graded copy signed by the artist. I dont know, i suppose you will get different answers from different collectors
These were not super expensive Spideys. Most were in the 113-157 range.