I have owned 3, and only 3 P-38's in my life. There were all shooters because they had been reblued, or were parts guns... As finely fitted as they were, they are still outshot by any run of the mill Luger P.08
Their accuracy is adequate for combat purposes, but you'll never see one set up for serious target shooting because of the sliding barrel.
I used to tell folks that they were like LIGHTNING!... they never strike twice in the same place.
The 7.65mm P-38's are a rarity, and I am sure they would function well, but would inherit the same accuracy issues that the 9mm's have.
Just my $0.02