I love that dock. I had four HDDs in two of these docks connected to one of my servers for a bit. Same experience. A bit slow for large transfers but fast enough for HD streaming. I think the space between the drives allows for enough natural airflow to keep them relatively cool. I think the hottest they got was 63 degrees Celsius during a large transfers. Usually stayed a bit below 60. In my janky homebrew NAS I see temperatures around 50, give or take 5 degrees. The use case should really determine the build so that may be the best option for many, especially with budget constraints.
I use Upsnap on a low-power SBC behind a reverse proxy: https://github.com/seriousm4x/UpSnap
Before that I used the WoL feature on my Asus router.