I think we have to entertain the possibility that THE katastematic pleasures are simply ataraxia and aponia.
Ataraxia is the tranquility of mind that results from ridding one's mind of fears of death and the gods and obtaining a proper understanding of natural phenomena, and so on. I'm working on a good description of aponia. It's not just "freedom from pain" in a banal sense.
Ataraxia becomes the background of our experience. Once we really lock it in (*really* and truly lock it in!! I know I'm not there yet!), we approach our all our other experiences with that stability and tranquility of mind that can't be shaken or taken away.