I really wouldnt say they're aren't perfect on the (J), I was recently on an 179 on the J and on of its doors remained closed throughout the entire trip and when the other door closed to looked like they close completely shut.
I swear every time I ride a 179 it feels like I'm riding a death train, there was this one the and when I sat down on one of its seats I heard a lot of creaking, felt like I was about to fall through the entire train.