HELLO TONY!
Kelly here. Saw the Half Black at PeTown huh? He's MINE!
Kidding. Anyhow, they are one of the smallest of the pygmy or dwarf angels - only get about 3.5 inches and have similar dispositions as the others. Although in aggression it usually goes from greatest to least Flame-->Coral Beauty-->Lemonpeel with the Half Black being in between Coral Beaty and Lemonpeel. All angels require a very good water quality and will be the first to show signes of distress if levels are kept. Angels are also prone to bacterial infection, especially the eye it seems.
Just some info I have found myself, I was looking at the same fish. Had it on hold, but my boss told me he could get another one for me.
I think it would work great in your tank!