I own a 9mm version and like it a lot. I chose it over the Kpf9 because it had a way better fit and finish, I figured the internals would reflect the same quality.
I personally can't say I'm interested in a .40 version of the 709, as the 9mm is enough of a handful. But, I'm sure it will have the same quality of the 9mm version. Actually, if the barrel is lest than 4 inches I usually stick with 9mm.