Archive.org has now enabled a full-text search function, which means that those of us on quests for odd Victorian novels now have an even easier time finding them. Yay! (Yay?) It's not on the front page; begin a search in the usual box to get to the results page, where you can toggle the full search option. So far:
1) I've not seen any false positives, which is one of the most frustrating aspects of GoogleBooks' search function. (I mean, it's possible that a children's book about a teddy bear includes a reference to the Scottish Reformation Society, but, you know, it's not what I'd call probable.)
2) The function pulls up results in documents shared with GoogleBooks that GoogleBooks itself misses.
3) That being said, the new search function is still a wee bit buggy. Right now, clicking on results opens the document...and then generates a dialogue box informing you that there's no sign of your search term anywhere. "What?!" you cry, outraged. Actually, it is there, but you have to run the search again inside the book.