From the top of my head, compared to ext4: RAM use and the ability to shrink an FS if necessary. Oh, also I’ve used an EXT FS driver on a Windows host, but I’ve never seen one for XFS.
Just to clarify, the previous comment asked about benefits of XFS over ext4. But I completely agree with your reasons for choosing ext4.
Rock solid may be a stretch. They still suffer from outrageous metadata bugs even to this day when used in busy file systems.
That bug alone has been open for over a decade. Development focus of the people who understand and want to fix those things have shifted to other filesystems like ext4 and ZFS.