To take #2 a bit further, I see a benefit in the 3 battery charger such as charging multiple batteries during one "set it and forget it" time period.
I seem to recall, not that long ago, one or more ops posting about problems they were having with the charging properties of a non-DJI charger cradle. If I had the time (which I don't), I'd search for those links. Due to the acquisition and replacement cost of OEM batteries, you may want to consider entrusting your batteries to OEM DJI chargers, but that's purely my own opinion.