Dear joemh; I would like to be giving you a more insightful response to your question. alas, the best I can tell you is that I appreciate your insight and obviously sound concern on this matter. It troubles me deeply that Christians can be SO very, very mislead and ignorant about this matter. I've broached this subject to both pastors and what I believed to be earnest God loving-God fearing Christians & always get a very negative response, very often an Adamant "NO WAY"! (usually the lay person) and a mumbled but firm "it was changed to Sun. to honor Christs resurrection" and that settles it. well, I'd like to know WHO has the authority to over-ride a Commandment!
one other thing I found interesting is a couple of seasons in my life I've attended church services on Sat. eve's for goodly durations and found several families that attended in order to honor the sabbath--but only spoke of it in hushed tones (perhaps having been admonished like I've encountered) these were separate church's--but the pastors of each were only having them at that time to try & obtain those who couldn't or wouldn't get up on Sun. am.
one last interesting note, someone might expound upon is the resurrection Sun. motive & that is (as If that were correct about Sun. replacement of Sabbath) I saw text that explained the actual resurrection would have been on monday--because two and a half days past between the crucifixtion & resurrection.
again my regards as to your knowledge, concern and articulation!