This may be a better topic for the Illumos ZFS mailing.
There are a couple things affecting your results here.
The SSDs perform best when multiple threads are filling their queue. In
your test you have a single thread.
It is my understanding the ZIL is also one thread per ZFS file system.
I've tested three SSDs in a Sun X4170M2. This server has 8 internal
SSD 2.5 drive bays with a Sun Storage 6 Gb SAS PCIe RAID HBA. I
believe the chipset on the HBA is a LSI SAS2108 (according to
http://tinyurl.com/koc6kdn).
I tested by adding each SSD as a ZIL for a pool and then running the
