I wanted to comment on these books.
We have used them a bit differently. Our very avid reading 3rd grader enjoys these, but in conjunction with the unabridged version. I will read the original and then he reads the Illustrated Classic. This has given him a great sense of being able to read the story himself, without it being too heavy. We also have been able to compare and talk about what was left out or how they might have worded things differently.
It has worked out really well for us doing it this way.
Yes, I always viewed the Great Illustrated Classics they way I did the Wishbone Series of books. My boys are older now and they bring Dostoevsky, Jane Austen and Shakespeare home from the library for "fun"! Your strategy will pay great dividends! Great job, Mom!