I'd go with the smaller unit.
I had a 10 cup Krups rice cooker I bought at the local Le Gourmet Chef we lost our lease sale. It also steamed and slow cooked. I never used it to full capacity for the 10 years I owned it. After 10 or so years it finally wore out and started shutting off before the rice was cooked, so I went shopping for a new one. I ended up buying another Krups, only this one was 5 cup capacity. It also steams and slow cooks, and in addition it makes oatmeal! I have found I don't miss the extra 5 cup capacity, my rice seems to cook faster in the smaller unit, and the other functions works just as well as the old 10 cup rice cooker did, but I do have to admit that I have never made oatmeal in it.
BTW, that is an awful lot of money to spend on a rice cooker. You can get the Krups unit, and I have never found any appliances of any kind more reliable than Krups, for between $65 and $80 American depending on where you shop.
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