I say eat the banana (or maybe half a banana, depending on its size).
The list of fruits on page 106 is really limited and I'm guessing that bananas aren't on there due to their higher sugar content (same thing with cherries, pineapple, grapes etc).
Ah, but then Pamela Peeke includes 1/4 cup of dried fruit on her Smart Carb list and dried fruit is WAY high in sugar ... and after all, raisins are dried grapes, right? Presumably you could have dried cherries, pineapple, and grapes, so why not their fresh counterparts?
If you have trouble with a lot of fruits and bananas work for you, my opinion is to go for 'em. Just keep in mind that they are higher in sugar than some other fruits (but also higher in fiber and potassium) and pay attention to calories and portion size. I
bananas but don't eat them every day. But I just finished cottage cheese with 1/2 banana and a little Kashi cereal ...