My reaction to the Wikipedia conversion article was similar to yours. I thought I was following it pretty well, but at the end I only had a vague overall grasp of what had happened. I think the issue was indeed the leap day factor, as manifested in the 400 year cycle. Still, I'm glad that as a twenty-first century person I can be content with the "add a day per century" formula in thinking back to those years. I still wonder if the average person, or even sophisticated ones, living then experienced confusion when forced to deal with people and places on a different calendar. I have this image of mail sent from "Ggegorianland" to "Julianland" arriving, on the calendar, before it was mailed !
