Cost/benefit doesn't work out in this use case:

- Less noise true, but peg a Mac Mini or MacBook Pro's hard drive to max and see if you can hear it from, oh, 5 feet away.

- This isn't a mobile device, so heat with regards to user comfort is not an issue. Until it presents a reliability problem, heat is a non-factor for a desktop.

- Smaller, and much more expensive per GB. Much more. Shaving another quarter inch off the enclosure also seems like a paltry gain for a much more expensive storage device.

- For a machine that reboots very rarely, this is moot. This is clearly meant as an always-on device (hence the low power usage to begin with) sucking down torrents all day or some such.

- It's a media-centric device. It will download stuff, listen to music, stream video... what kind of bandwidth does it need?

SSDs in a Mac Mini would be a Ferrari in a school zone - cool, and done purely for the sake of style, but let's not pretend that there are significant practical reasons for doing this.

For an always-on device you would actually fare better with an SSD than a 2.5" laptop hard drive. Laptop hard drives are not meant to be always-on. The bearings tend to wear out very fast unless they spend a fair amount of time spun-down. 3.5" desktop hard drives, 2.5" server drives, and SSDs have much better mechanical reliability in that respect.