First of all we are talking about post exercise. Thus the affect of LA on performance is of no consequence. So I am by no means saying that lactic acid will power you down the home straight in a 400m or 800m.
First you said that LA cannot be metabolized further to produce energy. I told you were wrong. In gluconeogenesis LA is converted to glucose which can be catabolized to produce ATP. Glycolysis and gluconeogenesis are both lengthy reactions. They are reciprocal and never occur simultaneously, otherwise there WOULD be massive loss of ATP and GTP. The two steps backward, one step forward WOULD be correct, if the processes occurred at the same time, but they don't. Glycolysis isn't able to meet the demand for ATP simply because it is such a lengthy and inefficient process.
Here's the easisest way I can explain my thoughts
After 20 seconds ATP/CP is mostly depleted. Muscle glycogen is converted to ATP through glycolysis. Since it is such a lengthy reaction, this system is not nearly as efficeient as the ATP/CP system. Therefore less ATP is available for muscular contractions. As the race continues this deficit becomes greater and greater. This result is the muscles become extremely fatigued. I feel this accute fatigue coincides with but is not generally caused by lactic acid buildup. After the bout is completed, ATP is at almost peak levels within a few minutes. Two effects still remain from the effort: high LA levels and depleted glycogen. Through gluconeogenesis glucose is synthesized from the LA and glycogen stores are replenished. I feel the LA mechanism serves a dual protective role.
1. While it is not highly responsible for the accute fatigue mentioned above, it is responsible for at least some of the pain felt during such efforts. This is similar to the CNS fatigue mechanism. Both act like off switches to prevent us from reaching complete peripheral muscular fatigue (otherwise known as death).
2. After restoring ATP, the next objectives is to regulate blood glucose and restore glycogen. Gluconeogenesis can synthesize glucose not just from lactic acid, but also from glycerol and glucogenic aminos (like glutamine), which would be derived form the catabolism of fatty acids and proteins respectively. Think of the way our hunter gatherer ancestors lived. Could they have afforded to have such catabolism occur everytime they chased an animal they didn't catch? It goes without saying there were no postworkout drinks. Which is a perfect segue to the original question (come on admit it. It really is!)
I think you're kind of splitting hairs. First, I believe malto is actually absorbed quicker than dextrose, so that doesn't matter much. I personally go with 2 malto to 1 dextrose. I think the timing you have is just perfect. Myself, I would go with one drink soon after, and have some oatmeal with protein powder mixed in and a lot of fruit. I workout in the morning so it's perfect for me.