A response to my friend
I was introduced to Reformation Sunday at a very liberal-catholic Lutheran parish, and no doubt its observance there was unorthodox. My pastor was a devoted ecumenist, had letters from Roman Catholic bishops on his office wall, and owned a biretta. When I walked into church on Reformation Sunday, I commented to him that I was uneasy with Protestantism. "I am not a Protestant!" he replied. "I am an Evangelical Catholic!"
The theme of the Mass was very much Reformation in general - he even tied in his views of same-sex blessings during the homily. As an Anglican, I see myself as both a Catholic and a reformed Christian. Throughout the calendar of saints, I celebrate my church's catholicity, so I don't feel bad celebrating its Reformation heritage once a year. Errors *were* corrected at the Reformation; I acknowledge that for the most part they have been corrected by Rome since then as well.
That's how I celebrate Reformation Sunday with a quiet conscience. I'm probably not typical, and there are likely parishes (probably Misery/Wisconsin Synod, or one of the non-Lutheran denominations that celebrate it, like the Christian Reformed) where it is an occasion to glorify Protestantism. But the bottom line is that I, a decided non-Protestant, have no objection to Reformation Sunday in principle. (Though, like a true Anglo-Catholic, I would rather celebrate Reformation Day with a High Mass on October 31 than transfer it!)
This year, I hope to go to St. Peter's Estonian Evangelical Lutheran Church in Toronto for Reformation Sunday. Their English mass is early enough that I can still make it to my own parish ("the Church of the Nearest Sunday") for my regular mass. (Although, I'm possibly revising my Sunday morning schedule on the second and fourth Sundays of each month - details soon!)