I made half this recipe for 2 of us and i and it was good buy not great - edible in my opinion. My husband liked it better than i did. i added some diced ham that i had on hand and add the shredded meat from the ham hock that i used. Needs lots of salt and pepper. Was just fine for a week night.
You are cooking the protein not the beans and melding flavors. With my experience canned beans can be in the slow cooker a long, long time and they are always the same.
I don't think it is a good idea to cook canned beans for 4 to 5 hours. I think there may be a mistake on this recipe.