If the only issue with pre-screen was cost, I'd pre-screen every single book I sent to CGC. At $3/book for the ones that fail the pre-screen, it's a bargain compared to paying the slabbing cost for a book that's coming back lower than you expected to be.
Alas, the real issue with a pre-screen is that it requires a 50 book submission, which is a bit out of reach for most non-dealers who send books to CGC.
Anyway ... much like Walking Dead #1, I wouldn't hesitate to slab 9.6 & above copies of Chew #1 - you never know, you might get lucky and have it come back a 9.8.
Well said Michael