Wait for the 9th edition. The 8th was a bit of a disappointment, has a few rather nasty errors in it (among other minor errors), and lacks a lot of data on their new bullets and Hodgdon's new powders (just a few of the reasons they're issuing a new manual only a year after the 8th was released
).
If the "beta testers" determine that the 9th is a let down, as well... you'll probably be able to find an even better deal on the 8th edition.
If you chose to go with the 8th edition, you could manually correct the errors via the errata on the Hornady website, augment the data with Hodgdon's (for the new powders), and, if you want it, grab the LeveRevolution data from the Hornady website before they take it down (since it should all be in the 9th ed.).
Skip the Sierra manual (unless you use a
lot of their bullets). Instead, send them an email complaining about how out of date it is, and that the X-Ring (their newsletter) is no longer providing load data updates. Follow up with the same complaint in a phone call.
The Sierra manual is a dinosaur.