As regards the actual 1898 recording, it shows something interesting: his low notes did worsen as he aged, and likely were not always as awful as they are in most of his commercial recordings. Lots of reviews talk about how great he is in rôles like Tannhäuser, whereas when he recorded the arias, he struggled with C half the time. Not ideal. He recorded Abendstern four times, and the cylinder is the lowest key he recorded it in.
Not perfect evidence, but it's what we have, and it is analogous with Ruffo's career.