I've had and used both very successfully. I currently own several G34's. We just haven't had the success with the .40's that we had hoped so I don't carry that anymore. I sold all my .40's and switched to 9mm's. I have used my G34 more than any other gun in the last few years and find that it is the best gun I have ever had. It always works, always hits where it is aimed and looks super. This is my latest one.
“The ultimate aim of martial arts is not having to use them”
― Miyamoto Musashi
"The only gunfight won is the one avoided."
― The Rukh