I'm thinking about buying the black SP and changing the frame with the frame from the white model which I assume is pure aluminum? unless they coated it white
It is aluminum, but not anodized. The paint fells off after several months (5-6 months), like in my unit. I used to have a white model and the aluminum was painted too, just like my current black model. However, now that the paint is peeling off, I can confirm that below the painting, the aluminum is still black, but I guess it's just ugly black.