Yeah ... if I was needing a bigger storage device, I'd really want ZFS too. The downsides though are it needs significantly more RAM and CPU-power for a good sized ZFS installation.
I basically did. I used FreeNAS a long time ago. Went through various other incarnations for NAS including a QNAP device. OpenMediaVault was my dream come true, as I was able to install "headless" Crashplan on it easily being just vanilla Debian-based. Can't do that on FreeNAS/BSD (easily at least). Can't do that on NAS appliances like QNAP either (though I think there is a 3rd party unsupported plugin for Synology devices now).
I've been using OMV for over a year now and it works great. ZFS would be nice, but having vanilla Debian, and the "world" of Linux software, is better for me personally. I was running a RAID 6 originally with OMV (software raid, no hardware raid card) with an external enclosure. I really didn't need that much space, so downgraded my hardware to just mirrored 3TB data drives and a 80GB 2.5" system drive in a really low-powered machine.
All depends on your needs.