Commodity hardware seems a good/cheap option - and I don't know, this might be fine for them.

I built a couple of racks for clustered decryption using commodity hardware; after a few months "burn in" the failure rate proved to be way higher than expected. Which, when you think about it, is logical - they are running 24/7 (compared to if you were using the hardware "normally").

After having to replace three servers inside a month we started to cycle into server hardware. This was a lot more expensive up front, but is reliable and the failure rate is almost non-existent in comparison.

So; buyer beware.

Even so; it is good to see someone else hacking together their infrastructure :)