I'm not familiar with the protein shakes you are using. I make myself a smoothie for breakfast most days with soymilk, frozen fruit, reduced fat peanut butter and a small banana. It works great for breakfast while driving and it is a good source of protein and fiber so it keeps me full for a while. The calories (250-300 depending on which fruit and how much PB I use) are appropriate as a meal for me and I have lost 64 pounds so far.
So the big question is: Does the calorie count and nutrition fit into your weight loss plan? A shake that is meant for bodybuilders and is very high in calories is probably NOT a good idea if you want to lose weight, but if the calorie count is lower, it should work just fine.