Sounds pretty well setup. I agree with Dirk about the record size. We've found that 16k is a pretty good sweet spot as your I/O will be fairly random with your majority of VMs seem to be J2EE web servers. You could consider have one share with a higher record size for your higher throughput/sequencial I/O VMs and lower record size for everything else (mixed loads).
Also, depending on what your 2 zil devices are, you could overrun them with 10 mirrors with the 15k drives. I've seen it.
This is a good thread to start for ZFS/VMware in general, not even that specific to Oracle ZFS.
Cheers,
Matt