The Recommendation here is a bit questionable though, the caveat(s) is (are) simply too big. At least HP probably won't use the "seal" in their marketing.
The noise/fan control issue is the only real negative, and it disappears when RAID is engaged. It's very quiet, I would not have any desire to mod it for more quiet -- its role is a file server so it won't be front/center in any room. If you can live with the built in RAID 0/1, then there's nothing to compete with this box at market prices. The Amazon ad on the last page shows a G2020T base build at $471. It's really tough to do better in a complete 4-bay mini-server.
I'd be curious as to what speeds you get with a simple file copy of a single large file. With the above setup, copying a 1.6 GB file gives around 95-100 MB/sec, which is consistent with the 800 mbit/sec from iperf.
Moving big video files around (2-6gb), I typically get 80~100 MB/s. It's the folders with multiple smaller files that slow the system down -- and the 10x sequential repetition we employed on some LAN speed tests. I recently copied 200GB of photos over the network, most files were 6~20mb, the avg speed seemed to be around 30~40 MB/s.