There is a significant additive advantage to consuming mixed carbohydrate and protein supplements immediately post-workout. Your post-workout target should be to both feed existing muscle fibers as well as stimulate satellite muscle cells. (which fuel the greater proportion of muscle growth from exercise). Progenex More Muscle does both.
Here are a couple of studies that you may be interested in:
Disassociation between the effects of amino acids and insulin on signaling, ubiquitin ligases, and protein turnover in human muscle.
Effect of pre-meal consumption of whey protein and its hydrolysate on food intake and post-meal glycemia and insulin responses in young adults.