I’m personally running nodes on ext4 with the 64bit option set, as most of changes it makes to data structures should not have measurable impact. However, as I’m also running with inode size set to minimum possible (128 bytes), there’s no space for 64-bit checksums specifically for inodes. I believe that the reliability expected from storage nodes can be achieved without 64-bit checksums.
I’ve done some experiments on tuning the number of inodes (and some other parameters) here: On tuning ext4 for storage nodes I hope you will find these notes useful. largefile4 is too large for Storj.