That sounds perfectly reasonable. We've already started out in that spirit with discussion of the original version of the Foreword. A few references to points of interest on how or why certain elements developed would be, I think, generally interesting and not exclusionary.
More in-depth discussion of a particular point, or of aspects of HoME which might not fit well here, can be carried on in the
Chapter-by-Chapter HoME Companion thread that I've set up in Books.
We'll start with one thread for now and see how it goes. We can easily expand to, say, a thread per HoLotR book if it looks like the conversation will bear it.