i really like steel cut oatmeal. Don't eat it often because of the carbs. When we have a bunch of guests over though oatmeal in the rice cooker makes for a very low drag breakfast item.
We have a Zojirushi NS-MYC10 rice cooker. This is a "fuzzy logic" rice cooker with a porridge setting, which we use. The magic ratio of steel cut oats to water is 1:3. For our particular model, we seem to do OK with 4/3 cups of oatmeal and 4 cups of water. Almost certainly could do an extra third, and perhaps an extra 2/3, cup of oatmeal with attendant water, without having boilover or mess problems.