High protein diet

We just got our first standard and I was talking with the breeder about food options. She feeds an endurance food that has high protein (33%) and talked a lot about how poodles need a high protein diet because they have a fast metabolism. I know they are active dogs, but she breeds show line, with some agility dogs, and the puppy we got is 15 months old and not super active or crazy.

We have a 12 year old rough collie that is on Hills prescription joint food, and I checked with my vet that switching the puppy over would be safe. The protein content is only 17%. I really prefer to keep them both on the same food if possible, plus the extra joint support for new puppy is a benefit, but do poodles really need a high protein diet? I've started slowly transitioning her and haven't seen any allergies or sensitivities come up, but what changes might happen if I keep her on the joint food with a lower protein content?