We shouldn't be singing much of anything that hasn't passed the 100-year test. 200-year test is even better!
The Episcopal Hymnal is full of grand old Catholic hymns -- if you look in the back for the source materials, there is Gregorian chant all over the place and old (15th-16th c.) German Catholic hymnals as well as the standbys everybody knows (like "Crown Him With Many Crowns" and "The Church's One Foundation"). Really they have done a better job of conserving the Catholic musical patrimony than the Catholics have.
I'm going to give our music director the large organist's edition (spiral bound in cloth; two volumes) for Christmas.
I'll have to get me one of those sometime!