I have owned a PX4 in 40 cal before. I just got one in 9mm a week or so ago. Great gun. Shoot fantastic.
I personally prefer a DA/SA over a Glock trigger (I've prev owned 5 Glocks in years past).
I switched from a mixture of 45 and 9mm to all 9mm now. I shoot better with 9mm over longer distances, and its cheaper to go shoot. After looking at all the data, I'm satisfied with the ballistics of the 9mm round. I carry a Beretta 92 FS concealed everyday, and am fine with it.