It is, but you'll have to update all your 32-bit programs (which is why I'm not doing it).I share this concern ^^. I'm running a 5,1 that was refurbished with a new 12 core some years ago. It's great today but not sure if Catalina is possible or not.
As I just said, for $1K it's a great machine. For $2K it's not as good a deal - although all Macs are more expensive in Europe, from what I understand, so the scale is shifted.