Hi sean0712,
While some version of the main Official Guide is used by almost all Test Takers at some point during their studies (and sometimes multiple versions of that book are used), the subject-specific books are not nearly as popular. As such, we have not documented the changes in the Quant-only and Verbal-only books - the 'demand' just hasn't been there.
Since you're asking about those books, I have to assume that you've put in some serious study time already. If you'd rather discuss your situation privately, then you can feel free to reach out to me directly via PM or email.
1) How long have you studied?
2) What study materials have you used so far?
3) How have you scored on each of your CATs (including the Quant and Verbal Scaled Scores for each)?
4) What is your goal score?
5) When are you planning to take the GMAT?
GMAT assassins aren't born, they're made,
Rich