I have never won a head on knife fight with a tactical knifer even when I switch to the I can use comando too class, I never unlocked the tactical kife though. Unless they didn't see me or I came from behind them I never won the fight. So unless they just nerfed it I don't think anything has changed. I have noticed I have been missing some easy knifing though but I thought it was just lag.
i myself have came to the conclusion that commando is a Bull**** perk. when i have it, tac knife or not, i get stabbed. my stabs always missed, EVERY time. just to get stabbed right back. i turned on sitrep and had so much more accurate knifing. no falling damage just dont cut it on that waste of a perk.
ok i did some testing and tact knife with commando does actually work, it just feels like half the time it doesnt but it does, it seems like its not as good just because the animation but its the same as regular just faster, and you can still lunge 15feet with it.