BevS; Some people also subtract sugar alcohols, but this can be self defeating since a lot of sugar alcohols raise your blood sugar levels.
Yes, I've heard some folks "stall" in their weight loss when they eat the bars with glycerin and sugar alcohols. I think your suggestion to have half of a whey isolate shake is good.
Muscle Milk now makes a powdered shake product called PROTEIN PLUS--it has 26 grams of protein, and virtually no fats / carbs. It's whey and casein proteins--if you read the label you'll see the benefits of both. Anyway, it's very tasty when one scoop is mixed with about 6 oz of water. It contains some sodium and potassium (electrolytes) so you can trade it for some of the IP stuff if you do your math.