We stayed at Mario's place with our 7 month old baby.
Great view and close to a lot of landmarks. Slightly uphill with no elevators and a lot of stairs, but totally worth it. Not a lot of space, but good enough to get some rest and hot shower. One of the best airbnb's during our Europe trip. If we managed to stay with our infant baby comfortably, then it should be great for anyone.
Thanks Mario for everything. Will surely return and recommend to anyone visiting Porto.