No, I wasn't aware of SUMACC. It was before my time. Very interesting stuff. I don't think it can compete with good old THINK C though
.RMaker was available on the Mac, too, and was basically the predecessor of Rez, which was introduced a few years later with MPW. It's a much simpler tool that only supports a few standard resource types, while Rez is extensible (and has a nicer syntax).