1.) Optimum signal transfer.
Optimum in what way? That's kind of generic, like "it's better because it is better."
2.) No need to go through the unit's inversion circuits to convert to SE at the preamp and back to Bal at the amp. Thus eliminating two inversion steps for the signal.
There is no conversion to SE at the output of a typical preamp. The non-inverting portion of the balanced signal is used for the SE output and the inverted signal simply remains unused. I agree with your point about converting to balanced at the input of the amp.
3.) Better signal-to-noise ratio at the amplifier (since it doesn't have to work as hard to produce the same output.)
If it is producing the same output then it is working just as hard no matter what you feed it.. Once the conversion is done at the input it acts just as if had been fed a balanced signal.