In the early '80s, I went through a phase where I thought "Let Heaven Rejoice" was the only proper hymn with which to open Mass. Thus, if I saw an opening hymn number other than 7, the page number of the hymnal in which it appeared, posted on the board by the organ, I was slightly irked.
I'm no longer that tightly wound. Today, I'd also accept (and actually prefer) "Christ The Lord Is Risen Today."
I suppose I've mellowed--slightly--over the last 40 years.
