In my opinion, the P07 is a great substitute for the G19. I feel it carries identically to the 19 (with the added safety of a hammer), and performs even better, IMO. I just tried the 5x5 drill for the first time today, and was surprised to see a time of 17.49 seconds- I know for some around here that is not an impressive score, but I'll take it!
I don't want to presume to speak for Mr. Langdon as I'm sure he has his own reasons. I'll share mine if you care to hear them.
The DA first pull provides the shooter with a bit more time due to the length of pull to make the decision to NOT shoot. A striker fired or SAO does not.
Men freely believe that which they desire.
Julius Caesar
I'd say a Sig 2022 or the 229, still, there is NOTHING out there that perfectly mimics the G19's mystical size:shootability:capacity:concealability ratio
I want that hair to be as thick as possible. My research and personal experience have led me to believe that there is no difference in reaction times and first shot. There is however, personal experience that has taught me that that little bit of clearance provides me with enough time to think when reacting under a startle response.
Men freely believe that which they desire.
Julius Caesar
I've been following Langdon's experience with the Beretta PX4. Sounds like a good option to me.
Jesus paid a debt he did not owe,
Because I owed a debt I could not pay.
I like my Walther P99AS in 9MM as my choice for a DA/SA pistol close to the Glock 19. Both have polymer frames with 15 round magazines. The Walther still has the teniffer finish Glocks use to have. Both are striker fired with little protruding controls.