I just happened to have been composing a 'blurb' about that very thing to go on this web site. I took a special interest in them this year after purchasing a little paperback book entitled McGuffey and His Readers, Piety, Morality, and Education in 19th-Century America
by John H. Westerhoff III.
As a result, we invested in the purchase of the original (1836-37) hard-cover version from Motts Media last month. All the versions of the McGuffey readers are great reading (the curriculum has the 1879 revision) so, be sure to use the set you already own if want to save the expense of printing.
If you are like me, you will make your own comparisons but, I would encourage anyone to read Westerhoffs's book to get a well studied comparison of all the versions as well as an eye-opening to the changing of the American peoples beliefs and values as it is reflected in the revisions. The originals are filled with Scripture excerpts, the Soverignty of God, salvation etc..
The revisionists thought it best to take this out to fit a changing, pluralistic nation! Yet, even the revisions, in light of our 20th century, have refreshing moral content, a rich assortment of literature and the occasional acknowledgement of God.
You may be interested in getting the full set of the original McGuffey's from Mott Media.
In our use of these readers the children have been simply READING THEM INDEPENDENTLY. Of late, as I am incorporating some ORAL READING into our weekly routine, especially with the older children, I find these books to be ideal...for many reasons.
First, being readers, there is an appropriate reading level for each of my 'school-age' children.
Second, they are already broken into short stories or lessons.
Third, the content is wonderfully suited FOR INSTRUCTING CHILDREN of Christian households and lead to much relevant discussion.
Fourth, each lesson has its own VOCABULARY list, with pronunciation helps and the fourth reader (as far as we have progressed) has word definitions as well.
Fifth, I find the 2nd reader to be especially useful for COPYWORK as each paragraph is numbered making it easy to identify a selection for copying.
As we now own a reprint of the original readers, I am reading these lessons to the children 'over' the occasional lunch . The 2nd, 3rd, and 4th readers in the original version include questions after each lesson. I am presently evaluating the parent-teacher guide by Ruth Beechick (wrote specifically to complement the original readers) as to its compatibility with the 1879 version. So far it looks very probable.
Although lesson examples/stories differ, the teaching suggestions are wonderful. not only for the 'teaching reading stage' but also for grammar and spelling instruction. The purchase of this guide could give the Robinson curriculum users even more 'mileage' from their McGuffey readers. Look into it if you will and I will likely give you further updates on the matter myself.