Easing the slide forward or inibiting the slide from moving forward quickly will make most semi-autos jamb more frequently. On the PX4 the saftey sits pretty flush with the slide. If it were any slimmer I wouldn't feel like I could release the safety quickly without looking. The rear slide serations are position enough ahead of the safety that it is easy to grasp the slide securely ahead of the safety. You should pull the slide back and open your grasp on the slide crisply like you would when shooting a sling slot. Alternatively the ergonomics of the PX4 are so good it is also very easy to safely realease the slide stop with you right thumb without adjusting your grip.
That said if you are shopping I would look pretty hard at some other guns before settling on the PX4. It is reliable, it is comortable for most people, it has the necessary features for a concealed defense gun, but if you are going to take it to the range and want something that will allow you to improve and shoot really close groups I'd look at something else.