I used to have a 6L (I think), so that we could cook a joint, or whole chicken. However we never actually used it for that in the end. For me a chicken or joint is better roasted in the traditional way… However we did regularly feed five, and there was always a couple of portions spare for lunch the next day (guess you would easily feed 6 adults). We generally did stews or currys, and cooked the potato / pasta separately
I now have a 1.5L cooker which is great, I use it most days, just chuck something in before work. Even just put sausages, beans and potatoes in last week… yummmm the ultimate comfort food ready and waiting for you 🙂 That feeds two quite happily.