So let's create a scenario where you stuffed down a high fiber meal and you needed to go to the bathroom, however rather than take off all your gear you decide to just transform to do your business, what form would you prefer to poop in?
Few concerns before you decide. How could flight form hold all your poop? Does your poop have the same makeup between forms or changes to your forms digestion? If you pooped as a bird would you theoreticaly drop giant logs from the sky?