bdp24,
You lay things out very clearly, addressing the questions I'd been ruminating on.
I would think Magnepan would prefer to do the X mods before they close up the speakers? If done after they are built, that might explain the $4K used mostly for labor?
If and when I get a pair, I'd most likely go down the GR-Research path.
If I don't get them, I will order the GR-Research kit for my 1.7i's.
Anyway, it's good to have something to dream about. And options.