I just aquired a J4 Slim and used it for the first time this morning. Had a wonderful smooth shave using a Derby Premium blade. No tugging, nicks or irritation. It has a nice weight and feel to it - very happy addition to the stable.
Welcome to the ranks! You are going to love your Slim.
The Slim might be the best razor ever designed and sold. (OK, maybe a bit over the top)
But I've been using mine for over 40 years and have not found another DE that is better. Some get close, but I will go to Valhalla with my Slim in my hand.