Hi..
I took the PCAT Kaplan Online course so I have the materials from there. However, I recently checked out from the library the 2007 Kaplan PCAT Edition from the library and compared the two books. While the majority is the same, the Organic section from the non-class book lacks about 90% of what is included in the book supplied by the course. Of course, I think a lot of what was included in the class book was superfluous (at least according to what was on my pcat). However, if you rely solely on the limited material in the non-class book, I think you're at a disadvantage because, as you noted, it's really "barebones." Having said that, it's not necessary that you purchase the Kaplan course solely to gain access to all the missing Organic mateiral; I'd look at the Exam Krackers (which is still overkill for pcat organic, in my opinion based on my test) or really any Orgo chem review book or text and go through the main topics. Although the amount of o-chem varies on each test, it's better to be prepared while still remembering that this is not an o-chem exam, so you're not going to have to know the material to the same extent.