Can a rice cooker make amounts much smaller than its rating?
As I note in my answer here, I use the exact model you are considering. It is one of the best gadgets I've purchased. It has no problem making any batch down to 1 cup in size. Being able to cook the full 5.5 cups when entertaining is invaluable as well. 

I will sometimes cook more than I need for lunch the next day, as well as making fried rice for the following night's dinner.

Bottom line: you won't regret the purchase.