I agree with you entirely, Theresa. "Opus", in its sense as a collection of music based on some underlying theme, is not "work" in the sense of the Latin original, it is a collection and the word is, by extraction, now an English one. So using the English plural logic giving "opuses" is correct.

However, my logic falls on its basso profundo when you use "opus" in English in the same sense as its Latin meaning. At which point my logic would, of course, have the plural as "opera". Which would make no sense to those with a small or shaky (or non-existent) understanding of Latin third-declension nouns. Hell, I studied 'em, and my understanding is very shaky these days.

- Pfranz