Well, I received my order of Acqua di Parma Colonia bath soaps, and I test lathered one with a brush and scuttle. It required quite a bit of work but did make fairly good lather, which improved markedly with the addition of a 1mm x 2mm dab (about the size of a pencil lead tip) of AdP Colonia shaving cream. Not the thickest or creamiest of lathers, but of moderate quality. It's definitely worth trying with a real shave, which I'll do sometime in the next couple days.
John