Manhattan GMAT Sentence Correction and Critical Reasoning

I just postponed my GMAT till October 10th. I feel like if I buy both the Manhattan SC and CR books, I'll have enough time to finish them before the test (even going at a leisurely pace). However, I took a Kaplan course and have the Kaplan book. Considering they have their own strategies, which I know, is there a point in shelling out the money to get these two books or will I not learn anything new from them?

Here are the books that I have from the Manhattan GMAT so far and my thoughts:

1) Word Translation- Loved it. The most difficult material from the math books that I had from them. That's probably because this material is in fact the most difficult in the quant section. Even the easiest Word Translations are more difficult than some medium difficulty numbers property questions. I feel like this taught me some strategies that Kaplan never taught me. Such as the RTD/RTW table. The anagram method (though I don't use it much, for some reason I find the regular formula more intuitive).

2) Numbers properties- Pretty good. However a great majority of it was stuff that I can easily solve. However things like number of factors might help on test day. Also helps with many data sufficiency problems.

3) Geometry- Good book. Some of the stuff it goes over, is stuff that I got wrong before on CATs and wouldn't have if I knew it. Like the largest possible area of a triangle when you know 2 sides. Also, similar triangles. Diagonal of a rectangular solid. It seems like it didn't go over the hardest problems (polygon's within polygons etc.)

4) Reading Comp- I was mostly disappointed. Although this is probably my least favorite section of the entire test. So that may have biased me against it. But it seems like it didn't teach me anything new.