I like the Buddha backdrop :-)
For some of the images I think you could use a flat colour before reducing the number of colours to reduce the dithering in some parts. E.g. you could use a flat blue background for Buddha and use a soft copper rainbow from slightly darker blue to a softer blue.
@haywirepc
8colours will work on ECS at useable speed, 16 won't.
For 4 colours the WB 1.x palette looks nicer, I'd like to have 4-colour iconset that uses 1.3 palette