Purple heart has a high iron content and gets it's color from oxidation. After processing it i.e. sanding and planing it put it in the sun for a few hours flipping it after a few hours. The purple will return them put your finish on.
Great ideas, Demien. I pretty much flatten every board that hits my CNC these days. Between the possible snipe and tendency to use boards too small for the planer, it's just become habit to take care of it on the CNC. Also, love the idea of using it for plug cutting. I use dowels when making hand planes on my CNC and I've been wanting to use graduated sizes as a design idea. No worries on dowel sizes or materials any more.