Vol ix is The Roman Republic, 133-44 BC. I already had vol iii: The Assyrian Empire, and vol v: 478-401 BC.
And I also had vol x: The Augustan Empire, 44 BC-AD 70. One of the reasons I was especially eager to get vol ix was pp 866-876 of vol x: "Appendix. The literary authorities for Roman History, 44 BC-AD 70." I was eager to see what original sources might be available of which I was unaware.
Turns out I had already heard of most of the sources listed in vol ix's "Appendix. The literary authorities for Roman History, 133 BC-44 BC." Many of them I knew only from vol x's Appendix. And some, such as Lucan, were not considered important enough by the editors of vol ix to be included in the Appendix. (Lucan is included in the bibliography for chapters XV to XVII: "From the conference of Luca to the Rubicon," "The Civil War" and "Caesar's dictatorship," but only as a secondary literary source.)
What I hadn't thought of while admiring the Appendix in vol x, published in 1934, was the possibility, which turned out to be the reality, that it was an improvement in many ways over the Appendix in vol ix, published in 1932. It hadn't occurred to me at all that it might not have occurred to them at all to provide such an Appendix until after vol ix was published, even though vols iii and vol v lack such Appendices altogether. And there's no reason why the earlier volumes wouldn't have benefited from such a thing: a concise listing, within a few pages, of the ancient writers which had been consulted in the making of each volume of the Cambridge Ancient History. Somewhere between vols v and ix, it occurred to someone to include such an overview, and sometime between vols ix and x some improvements occurred to someone: separating extant from non-extant sources, and Latin from Greek ones, with subtitles.
What on Earth is the point of this post, you are very justifiably asking. Just my insight about how a long anticipation of something -- I'd been looking for a reasonably-priced copy of vol ix of the 1st edition for quite some time -- it may very well be that my reasons for eschewing the 2nd, revised edition are all completely irrational -- can lead to disappointment, because the reality of the thing will naturally vary from the imagined version. I'm not receiving this insight for the first time, but perhaps it will stay with me longer now. It was the same way when I saw the 1st edition of the Encyclopedia Britannica, and its choice of topics was so different from all of things which I had very much wanted to see described from an 18th-century point of view.