Garanca and Netrebko are possibly the prima-donna queens of this century (so far), I have especially enjoyed following Garanca for the last 24 years or so.
Cimbasso is a bit more common in opera than Contra (except of course, for Wagner). Much of the Italian repertoire like Verdi and Puccini was written for Cimbasso.
Lots of rests in the arias, but there can be some serious licks in the big tutti passages.
Aida definitely has some stuff - 16th runs that would be impossible on trombone. Plus an unusual walking bass line kind of thing that goes on for several bars. I don't think it goes below B, which would be the limit for a 3-valve F instrument.
Depends on the opera though - a few cimbasso parts lack anything technical and can be covered by contra or even bass.
I have heard that Verdi adds a comment in some of his scores along the lines of "sans bomba": no tuba.
90's Bach 50B3LOG with 3d-printed valve cores
Shires lightweight slide (yellow, nickel crook) with B2N leadpipe
DE XB113mW / L* / L8
Without getting into the full Cimbasso discussion (30 pages and counting on tuba.net), a lot of those verdi parts would have been for an ophicliede judging by the range. And, yes, a big tuba isn't right.
