The Hitachi 7k2000/7k3000 drives are not 4k - even the 3TB ones. I have tested 2TB 7k2000 and 3TB 7k3000 drives with the expander you're using, and they work fine (though I'd stick with 7k3000 due to the bug I mentioned before). The hitachi drives also don't have TLER, but your RE drives will. ZFS doesn't require TLER, but I can't remember if it's detrimental or not to have it.
Okay seems like Hitachi might be my next line of drives I will get 3TBs no real reason for 2TB drives.
I like to know if 4K drives are a problem with ZFS or not though?
I also hope someone else in here can tell me if TLER is a problem or not.