I'm not planning to pull the trigger on anything like this until early next year, so maybe this is all a huge waste of time, but what the heck.
I've currently got an Infrant X6 (more-or-less RAID5) box with 4x250GB of storage.
We discussed this earlier, but I ended up just keeping the thing. It's basically full, and while it does the job, it's not exactly screamingly fast. NFS will never equal local disk performance, even over Gbit links. More importantly, it's simply too loud to leave on all the time. This is a pain, for all the reasons you can imagine. My front-end box is a Mac Mini, talking to the Infrant box with GigE (but not jumbo frames). And, yes, I've got the Infrant box on a UPS, which allows it to turn on all the disk caches.
I've been pondering how I want to improve on this situation. Initially, I was convinced that I'd end up with a MacPro Tower with four bigger disks in it. Those are quiet enough that they won't be annoying to leave on 24x7. Unfortunately, Mac OS X 10.4 doesn't support RAID5. Your only choices are mirroring, striping, or an external box like an Xserve RAID, or other RAID enclosures.
This got me poking around. The rumor mill is saying that OS X 10.5 will include ZFS, and there's some evidence from early developer builds to support that claim. If true, ZFS would easily do the RAID5 thing with a MacPro Tower's internal disks, and you'd get fast snapshots and all the other ZFS goodies as well. At that point, the only missing feature, relative to the Infrant box, would be it's easy setup and a handful of really nice features (e.g., an Infrant box will email you when a disk fails, among other events).
Of course, ZFS is natively at home in Solaris / OpenSolaris and has been ported to FreeBSD. ZFS hasn't shown up yet in FreeNAS (built on FreeBSD), but that's just a matter of time. And, for that matter, one of my dream features for the house I plan to buy in December (or thereabouts) would be a utility / wiring closet where I could have a rack-mount server, real wired Ethernet to every room, and so forth. At that point, the noise issues go away, and the Infrant box (or a sequel to it) looses one of the biggest strikes against it.
One way or the other, having a "real" computer is looking more attractive than the Infrant for my file server. Like it or not, I'm becoming one of these Apple walled-garden types, where the idea of all the Apple parts just snapping together and working is increasingly attractive.
Thoughts?