Then in that case probably will want the King, even though its rated at lower flow with no head, it has a 50% higher head so it probably won't lose as much flow at the 1.5 meter ish he'll be running it at. So, probably come out ahead.
But, then again, either one will be heaps of flow, so if the Atman is the quieter one, probably worth it. I've never used either, all I use are Lagunas.