Untar and cat time
It is very common in the Linux world to distribute some very large number of quite small files using a compressed, one-file archive created by using the tar and bzip/gzip utilities. For examples, Linux kernel (downloadable from kernel.org) are distributed in this specific manner.
So, an interesting benchmark would be to record the time needed to untar (extract) the Linux kernel .tar.bz2 file, and then to read-back the just-extracted files:
While EXT4 is faster, the high-end RAID controller help XFS to remain in short distance from the leader.