In general, I have not been a fan of Abbado's Mahler. However, I have always held his CSO M5 in high regard, and I find this recording vastly superior to the live Berlin edition.
Coincidentally, last night, before I had heard about Abbado's passing, I played his CSO M1. I've been culling my collection recently, and It was on my out stack. I am pleased to say that it is an fine performance and recording, and that it has gone back into the main library.
In this recording, which I think was made in Orchestra Hall (venue and date are not mentioned), the CSO still sounded like Fritz Reiner's orchestra--the precision, the tonal beauty, and the uncanny impression that everyone was a virtuoso. Even if today's CSO is just as good, they can't sound like that in Orchestra Hall owing to the late-90s remodel.
Misgivings about Abbado's Mahler aside, I'll be revisiting some of my other Abbado/CSO CDs. The Prokofiev Lt. Kije and Scythian Suite are outstanding, to mention one example. I also like his Berg disc with the LSO, his Wozzeck from Vienna, and I'm sure I'll fish out some others.
As a guest conductor, he spent a lot of time here in Chicago and I'm sure many of our local music enthusiasts are saddened by his death.