I have the Lone Wold Distributors 40/9 barrel in my Gen 4 G23. I bought some G19 mags to go with it. When I run the barrel, I run the 19 mags and a gen 4 19 spring. The spring is me just being ANAL. NO ISSUES whatsoever. I occasionally get brass to the top of the head, but I wear a hat, so no biggie.
It's a lot cheaper to shoot and I still shoot on the same trigger so it helps me develop a smoother pull. Plus, I can now shoot 9mm reloads with the barrel, saving me more money.