The New Testament obviously does not observe the Sabbath, Paul told us "on whatever day". However, as a type it is very important, just read Hebrews and just because it isn't part of our covenant doesn't mean it isn't important, it is part of the Old Covenant.Nah .. I grew up Southern Baptist and we always worshiped on sunday.
Seems a little self-righteous to judge people just for what day they worship
Also Christians are not subject to Mosaic law, as per the covenant of the New testament so yeah, it's pedantic
In Colossians Paul tells us that the Sabbath days and holy convocations are prophetic, a shadow of things to come. Many pastors refer to Israel as "God's prophetic time clock" so if you are trying to tell time it makes a great difference. Also if you are navigating across the ocean it is crucial to have a good clock, you can't tell where you are unless you have a very accurate clock.