I never did and likely never will try to clone a Natty but I believe, and the books say the same, that cloning light BMCs are pretty difficult. Companies have optimized their industrial set-ups to produce them in large scale, which is difficult to reproduce manually in our homes. Besides, I think BMCs get a lot of adjuncts, or whatever they are called, such as corn syrup (USA) or sugar cane syrup (Brazil) as a cheap source of fermentable sugars, hence the lack of aroma and somewhat odd sweetness that most of them have.