i uninstalled ZEVO and installed OpenZFS on OS X and here are my observations:
1) I didn't copy my data, I exported the ZFS pool, uninstalled the ZEVO software, rebooted, and installed the OpenZFS on OS X DMG file. You may recall I installed one of the beta versions and gave my impressions on IRC a while back. I am running 10.8.5 on a 2008 Mac Pro with 32Gb of RAM. The ZFS pool is a 8x3Tb raidz2. It actually imported fine and reports no errors in normal day to day running.
2) iTunes library of mp3 files is acting very funny. Most of the older mp3s can't be found by iTunes. Its as if it has 'reset' the location of its mp3 library because it was missing during a reboot or something. As I have nearly 30,000 mp3's it is a bit of a pain. I am continuing to look at this problem. This is the biggest issue for me, for i am a flac person, but make a mp3 copy for my car/out of the house roaming.
3) ZFS scrubbing runs at a fraction (5%) of the speed of the ZEVO scrub. It scrubs too slow to actually finish my ~13Tb pool. ZEVO will scrub in about 30 hours, OpenZFS on OS X was estimating 225 hours. I let it run for about 8 hours and the speed didn't improve. I cancelled the scrub.
4) I have a 2nd identical 8x3Tb raidz2 backup pool (called backup, naturally) that I connect once a week and rsync the data from the primary pool to the backup pool. Things went haywire with the Finder while the backup pool was imported (with the same filesystems names but different pool names). It was almost like the finder was adding mounts and deleting mounts in parallel. Very odd. ZEVO doesn't do this. My finder options only have the 'primary' mount point displayed with the Finder.
5) My L2ARC SSD failed to be used - the cache wasn't accessed and didn't grow like it does with ZEVO. Now perhaps as a home user I don't really need a SSD L2ARC cache but it was nice to have and did speed up ZEVO's disk accesses to my large media collections (flac and MKV).
6) The most important point is , although L2ARC is currently not working for me and I can't do scrubs, it hasn't blue screened on my and is very fast and stable in day-to-day operations. Dare I say, it is a keeper. Congrats to lundman and ilovezfs and the other members of the OpenZFS on OS X team for a very worthwhile release!