I outlined my hardware in this thread: FreeNAS Alternatives - LUbuntu or Proxmox? - #4 by Peanut253
Basically AMD Athlon 64 x2 4850e and ASUS M3A78-EM. I also did some benchmarks and that 4850e is holding up pretty well 
,especially since it supports virtualization. FreeNAS and FreeBSD in general has a long history of not supporting old hardware and the developers do not care to because FreeNAS caters to businesses, not people setting up a home NAS/desktop.
Scope: I am referring to BSD in the context of FreeNAS/NAS4Free , not other BSD distros, and only in contrast to Debian, not Windows. And I am also putting aside for the moment that it doesn’t actually work on the hardware I need it to work on.
Debian and Linux in general has better support, both for the software packages I care about actually working, documentation to configure it properly and, in general, runs faster on the same hardware.
The BSDs are more…for stability/security oriented over performance or hardware/software compatibility oriented. This is not really surprising and makes sense for servers/NAS but that does understandably mean it has its short comings over Debian in compatibility and packages.
Honestly, the only real selling point for FreeNAS/NAS4Free for non-business systems was ZFS support and now that ZFS on Linux exists… FreeNAS just makes no sense over say…openmediavault. Or for a more virtualization centric approach, Proxmox, which can be easily configured to provide just as much security as BSDs in general. Linux with ZFS makes it possible to get all the benefits of ZFS, all the benefits of package availability, all the documentation available for those packages, have near everything precompiled, great hardware compatibility and decent performance.
When comparing the “plugins” list on the FreeNAS page to “all Debian software packages,” it is pretty clear which OS I would prefer to use.
