Gator, I've been around the boards long enough to know you are a serious dealer/collector, so don't think I'm questioning your expertise. I am just noting we we have a serious bidder on the boards (you) who would bid up to $500K and stating my own (different from yours) opinion as to how high your bidding rivals might go. In short, I'm speculating (e.g. guessing) based on my read of the small pool of collectors swimming in the deepest part of the pool. My opinion is based on what you are willing to pay and the speculation that others will pay more.
To be clear, I don't think the 9.0 is going to hit $1M because it is not the best extant copy. There's a MH/Church copy out there that sold for $176K 25 years ago which the OPG once rated at "mint" and others have said may range up to 9.8 (and no one has said is less than 9.0). BUT, I do feel in a world where the 9.4 AS 8 and 9.4 CA 1 are almost $1M books, the Whiz 2 is (or more accurately, IMHO should be) a $500K to $1M book, and closer to $1M than $500K. I admit that is rare air as examples of only 6 different issues have ever topped $750K: AC 1, D27, AF 15, MC 1, AS 8, and CA 1. But I think the best graded copy of Whiz 2, maybe the second best copy extant, could join that group.