This machine has now been chugging along for a long time. It stores about 4 TB of personal backups (all my machines back up to it over the network), and various other things such as projects, media files, photos. ZFS is rock solid. I've had drives fail, and the backup drive take over without noticing a single thing.
I've got 4 GB of memory in this machine and I can get write speeds over the network of 80 MB/sec using consumer grade drives, and read speeds over the network of around 120 MB/sec (I easily saturate my Gbit network).
I wouldn't store my backup bits on any other file system, I've had failures with various Linux based raids/file systems that were nonrecoverable, I've used UFS in the past from FreeBSD and had data be silently corrupted, end to end checksumming is absolutely fantastic!