If the rear setup is in good order I can't see why an upgrade would be needed. Mine are just fine. Ok so the disks look a little lost behind the 16 inch wheels.
Having tried a reasonably crude brake upgrade, the increase in braking power is unbelievable.
The TF160 is severely underbraked at the rear and the calipers also don't help as they just degrade over time and either don't brake enough or bind on.
I think with 4 pots at the rear, APs at the front and properly set up, it will be like throwing an anchor out the back.
I am a firm believer that you don't need all that braking power day to day, if ever. But, if there is ever one time you need it then it is an investment worth paying.
I would rather look back at the wasted money rather than the broken body of a child wondering why I hadn't done it.
You don't have to be doing daft speeds for you, or others, to benefit from upgraded braking.
If a lorry pulled out 30ft in front of me, I would rather stop in 25ft than 50ft.