Pros: Works great. I used this to replace my USB stick for my freenas box.

Cons: Price. It's a little pricey but at least it was in stock.

Pros: Fast, sexy

Cons: None

Overall Review: FreeNAS 9.3 uses ZFS by default for boot devices. Since there was going to be more reads/writes I wanted something faster than your typical USB thumbdrive and hopefully more reliable. I upgraded by doing the 9.2.1.9 upgrade on my USB drive, saving the config, installing 9.3 on the SATA DOM, then uploading the config. The web interface is much snappier than it ever was under FreeNAS 8.3 or any of the 9.x series, but since I upgraded the version at the same time it could be that the new version is responsible for some of the performance increase. As of 9.3, it is possible to create mirrored boot volumes. If I didn't care as much about performance, I would create a mirrored ZFS boot volume using 2 8gb or 16gb thumb drives. I have a couple of 36-drive Supermicro E1R36 boxes at work, and I will absolutely be going that route when I upgrade them to 9.3.

Pros: Small SATA SSD speed

Cons: Price?

Overall Review: I bought this to go into an ESX host for a business. Since the ESX install only takes about 8GB, I figure that leaves enough for if the SSD starts degrading. With the SSD, ESX boots very quickly. Total, maybe a 2 or 3 minute bootup including the RAID initialization of the 4 spinning HDDs on the RAID card.

Pros: - Small - Low power - High mean time before failure

Cons: - Specific to Supermicro or similar boards with a 5V power source

Overall Review: I've been using these for a few years now. There could be an academic paper comparing failure rates of boot RAID configurations with flash disk on modules, I haven't done enough research to say definitively, but my option is that these more reliable for installations with a modest volume of writes to boot disk.