I like to look at the big picture and identify my goals. A couple of points I think about when reading your post:
1. Just to qualify, yes, there will be children homeschooled with an entire classic approach that will do very well, in other words, there may be more than one road that leads to the same location.
2. I don't know much about classical, but you mention the first few years are rote memorization. This makes me once again look at the big picture and wonder where they will be in a few more years. I teach at the college level, and I spend all day trying to get my students BEYOND memorization to critical and analytical thinking. I actually have stated more than once that once they start memorizing, learning ends! Obviously that is a bit drastic; we do have to memorize some things, but my goal with my young sons is to leave the memorizing for last and start with theory and application.
One last example from work; I recently gave my students a pretest for a mock board. This was prior to our end of the program review. I tallied how many missed each question and first looked at the questions that 0-1students missed (very few). Guess what, they were all one-step memorization type of questions that did not require any analysis or critical thinking. The questions that were missed the most (very large percentage of the test) were higher up the pyramid of Bloom's taxonomy, in other words students had to go through multiple steps, critically think, analyze the situations, and so forth. Yes, the memorization is important for them to evaluate the question, but students have not learned to go beyond. My student's proved this with their 50% average scores on a test one semester before they are done.
3. It is much easier to retain information in memory if we have worked with it, applied it, learned it in a variety of ways, and so on. The fastest way to forget information is rote memory.
I don't know if that helps, but these are the things I consider when choosing how to educate my children. I want them to learn valuable skills such as critical thinking, application, following directions, etc., and I want them to retain what they learn as much as possible (and obviously we will never retain all of our education, but I hope my boys will retain more than I did).
Wife to J
Big J - Bigger
Little J - LHFHG 1/2 speed