EDIT: OpenZFS 1.7.2 fixed the issue!
I'm posting this here, to be on the safe side, but after many trials I'm quite sure the issue has nothing to do with my computer being a Hackintosh…
I had various issues after updating to v1.6.1 on Mavericks: to summarize, pools created after 1.6.1 prevent the computer from booting if the drive they're on is attached to the computer! (be it the boot drive or not)
Old pools don't create any problem and work ok.
• It happened once on my boot SSD (that had no ZFS pool on it before), where I created a pool for my VMs — I first thought the VMs could be the problem, so I replaced the pool with a HFS partition and it went back ok
• Now it has happened again to the HD where my long time first pool resides, after adding a partition to another existing pool, I had the same issue (impossible to boot with the HD attached)
=> the problem is gone when I destroy the recent pools and delete the partitions...
• After I fixed that, I created a new pool but to my amazement, it didn't mount after reboot, but the underlying HFS partition did instead! (I tried twice, putting data in the pool or not) — if I eject the HFS partition, I can manually import the pool and the data is still there…
I reinstalled v1.5.2, first on another drive, then to my SSD, in both cases, those problems are gone, so I have no doubt it's related to v1.6.1 (the Mavericks build?).
Note that I use drives with lots of HFS partitions and some ZFS pools. My use of ZFS is very limited for the moment, I'm far from the mirror or raidz thing…
As for that issue: I've controlled every accessible information and saw no error anywhere (pools status, Console).