Soooo, this new wave of pen style machines has me looking on in great anticipation. However, I am really concerned with the cross contamination factors involved, namely with the inner workings. If diaphragm sealed carts are not used do they get back spray all up inside of them? I also am still a little unsure about just how sanitary simply wrapping and then wiping the grip with germicide actually is. In theory if that is acceptable, then why shouldn't I be able to just use a disposable cart grip with a standard cart type machine over and over until the grip wears out? These are just some of the reasons why I have yet to use carts.