We did and we installed it and then the already huge stroller became a monster. It was heavy, cumbersome and we sometimes had to wait for a long time for an empty elevator to get on. I could barely push it.
You can use a head support device and just put the new born in until 3-6 months ( lying totally flat) when they have more head stability – just no running. We got this one and it has made all the difference in the world.