If you want two inputs then extra circuitry is always needed. You need either relays or a switch to ground the - part of the amp for SE use.
As for the T1S and W, they do sound different and some of it is due to the evolution of the circuit. Still that comment of mine is from the days before I rebuilt all of my amps and there are a lot more factors to consider then just the inputs and how they are handled. It is a simple fact that all electronics don't age the same way even if they are made on the same day with all the same parts.