To me you have already hit the nail on the head with your list of advantages and it is just decision time.
My question is - would you shoot both the same amount? In other words, if you got the KAC would you shoot it or look at it for the cool factor? (There's nothing wrong with that! I have safe queens!)
I play the "which is quieter" game too, but in the end I don't think it matters. If you shoot a TiRant and a KAC side by side you may be able to tell a difference in signature and possibly decibels. If you were to take just one to the range and shoot it and then take the other the next day I think you'd be hard pressed to remember a difference. All that to say either one will be fine.
Just my $0.02