Every time I've sandblasted something (old car/truck frames, motorcycle frames/gas tanks) it has left an almost pitted/porous surface (ie. harm to parent material)... that is on steel, would imagine that a softer metal like aluminum would be even worse.

As for removing the anodizing via reverse electrolysis, I've heard it works.

Also, I found (via interwebz) that a "dilute aqueous solution of phosphoric and chromic acid" will remove the anodizing without harming parent material... but you need to be an excellent chemist to do it without killing yourself.