Anybody that is serious enough to go into Macrobiotic cooking will know about the aluminium issue. Macro cooking is very specific and detailed and getting the right cooking implements is a prime factor so the alumium thing is pretty much a non issue in regards to Macro.
In Macro the pressure cooking is for grains and since we are talking about a very specific dietary regimen with its own "very specifc" reasons and since the subject at hand here is "Macrobiotics" I would encourage that you should do a little research specifically on Macrobiotics before making any declarations of what "is best".