I am not familiar with TMCC. I wonder if it's possible to design a loco that all function wires terminate in a socket, into which either TMCC or PS3 could be plugged. The TMCC or PS3 need not utilize every terminal on the socket. This could save Atlas considerable money on inventory. Buy an ATlas loco, and have the dealer plug in a PS3, TMCC, or conventional reversing unit.
Oh now that would be too simple, easy and convenient like plugging a DCC board into HO engine socket. Don't you enjoy wading your way through a maze of wire bundles wondering where that yellow wire goes or does, why is this white wire spliced into the green and blue soldered to the motor??? etc, etc ,etc