Interestingly, when repeating this random write test but increasing the size per thread to 128MB, Btrfs was the leader continuously while ZFS possessed no lead this time around. However, ZFS still was the fastest BSD file-system and faster than EXT4 on Linux.
Lastly, with a read test of 16 threads and 256MB per thread, all three file-systems on PC-BSD ran at about the same speed while Linux was much faster with EXT4 and Btrfs. Btrfs took another first place finish with a read speed of 57MB/s compared to EXT4 at 42MB/s and the others at about 15MB/s.
While ZFS has long been looked upon highly as being an advanced file-system -- it does offer a really great feature-set -- and something that various stakeholders have wanted on Linux within the kernel if the license was changed (right now the closest solution is running ZFS as a FUSE file-system on Linux since the CDDL license is incompatible with the kernel's GPL), the latest EXT4 and Btrfs file-systems are certainly great and are actually faster than ZFS, at least when compared to FreeBSD's latest ZFS implementation. The only time that ZFS on PC-BSD/FreeBSD 8.1 was actually faster than EXT4 or Btrfs was when performing random writes of small file sizes and a low thread count, however, once the number of threads became too high or the size increased, Btrfs immediately popped back to being the faster file-system. It is also noting that as our earlier Btrfs benchmarks have shown, when enabling the transparent zlib compression in Btrfs, its performance jumps up even more. Btrfs also has automatic optimizations for a solid-state drive.
While ZFS was not faster than EXT4/Btrfs overall, these results certainly show that this file-system is a superior choice to the UFS file-system options on FreeBSD. The performance of ZFS is certainly better than UFS and it has the much greater set of features. It would actually be nice to see ZFS enabled by default in FreeBSD in a forthcoming release or at least for it to be properly integrated with the FreeBSD installer like what has been done with PC-BSD.