My full explanation of the experiment can be found in this post.)
To wit, I have tried this with one book and, therefore, have a conclusive answer for you all.
The answer is, a brand new book can be enjoyable and comprehensible just listening to the audio.
So much so, that I'm completely captivated by Scott Westerfeld's Leviathan series and have the sequel, Behemoth, on hold in the audiobook version.
There was one plot point that had I been reading the book, I would have gone back a page or two to double-check. As it was with how it was tracked, rewinding wasn't really going to work. So, I just had to go with it and assumed that I missed a nuance or the track skipped or something. (I'm not saying what it was, because I don't want to put a spoiler out there.)
The other great thing about audiobooks (some that I've read for adults and definitely the kid and YA titles) is that the readers do voices. They don't just read the book, the vocally act the book. Leviathan was read by Alan Cumming who not only did changed pitches or cadences but accents for the Austrian, Germans and British characters. I think my favorites were his Count Volger and his Dr. Barlowe (OK, here's a shortcoming of audio books... I don't know how to really spell character names!)
Part of the original question was also about appreciation of the work. In the case, I think I was more appreciative to see how Westerfeld made an alternate history fit in a YA book that comprises steampunk, modern genetics, and warfare and still told a great story. Several times, I was nervously drumming my thumbs on the steering wheel to find out what would happen next.
Clearly, my deep scientific research has proven this question, that comprehension really isn't lost when delving into an audiobook as opposed to hardcopy.