Ok, the first article said
Milk, or tea or coffee made with milk, is treated as a solid because, with gastric juice, it forms a thick flocculate that takes up to 5 hours to empty from the stomach.
The second article made no reference to how the consumption of milk with coffee can affect its absorption or digestion. It simply stated the drinking milk with coffee probably won't help heartburn.
OK. So milk forms a "flocculate" in the stomach. Does that imply that the caffeine is absorbed more slowly? I don't think we can day definitively until we answer the following questions;
Does the caffeine stay mixed in with the flocculate once it forms or does the milk separate out and allow the caffeine to pass through the stomach?
Where in the GI does caffeine absorption occur?
SO here's a possibility: cafeine is absorbed in the stomach lining, and the caffeine stays in the milk. In which case, maybe it actually INCREASES absorption because the flocculate spreads around and coats the stomach, allowing the lining to absorb the caffeine.
Obviously there are several more possibilities, but, IMHO, I don't think drinking a latte gives you any less of a buzz than drinking the expresso straight. Otherwise lattes wouldn't be so popular.
Interestingly enough, the second article said that caffeine does not cause osteoporosis and that you don't need to consume EXTRA calcium, just to make sure you are getting enough.
So the point I guess is rendered moot.
Finally, from a personal point of view, I think lattes wake me us as much if not more than black coffee so my advice would be
If you like to lighten your coffee and also would like to minimize fat, use skim milk in your coffee.
JC