I'm glad to hear you might consider giving the low protein diet a try :). Also keep in mind that if you decide to have children the diet is especially important. Women who have PKU (all forms of PKU) need to adhere to the low protein diet carefully in order to have a healthy baby.
Following a true low protein diet without the metabolic formula can actually be harmful to your health. The formula gives you all the nutrients that you are missing, because you are not eating other foods. The formula also provides you with all the protein you are missing from your diet minus Phenylalanine (phe) which is the amino acid in protein that is harmful to those who have PKU.