One thing I am pushing to do is using SSDs for the ZIL and L2ARC. This would allow for a pretty nice boost in speed.
I use ZFS on freebsd as my large production server configuration as well. I have SSDs for the L2ARC and that works *really* well. I do not use a ZIL at all. Using the ZFS compression is a big win, along with all the other management advantages you already outlined.
There is a minor speed penalty, but the other advantages far outweigh those. That and throwing 256GB of RAM at the problem makes it more or less go away.
