Yes thats an option but ext4 is severely lacking in comparison to ZFS.
As far as I know ZFS is not available in Linux kernel, on other hand I've read that ZFS is slower than UFS on FreeBSD which is slower than ext3 on Linux.
I am aware of the fact that ZFS cannot be used with Linux because of licensing differences. That's way I was after the best possible alternative. Openindiana looks like a good option but it's in development, no stable release yet.
Can you please reference your source about ZFS being slow on FreeBSD - I was seriously considering this option.