Will the Touch use the same PS as the SB3?
The stock switcher for the SB3 is rated for 5 volts and 2 amps.
The new power supply that comes with the Touch is rated for 5 volts and 3 amps. If you are not using the USB section, you might be able to get away with a lower current PS.
In beta testing, it was found that some items did need more current than the USB spec allowed. It depends on what you plug into the Touch as to how much current it actually will need.