The usual reason to prefer ARM is efficiency, and the author's mention of replacing "power-hungry HPE towers" seeems to support that as a primary motivating factor.
True. But as detailed in the Jeff Geerling article that was shared here in the comments, it has (at least at the moment) a rather high idle power draw, which seems to negate that, especially over time.
True. But as detailed in the Jeff Geerling article that was shared here in the comments, it has (at least at the moment) a rather high idle power draw, which seems to negate that, especially over time.