I'm not au fait with modern autothrottles (obviously!) but if you have the AT controlling the approach speed what happens if you command more thrust? Does it let you move the throttles or do the throttles move but when you take your hand of them they try and restabilise at the commanded speed? In otherwords if you need a handful of go and need to manouvre hard both hands say to avoid another aircraft will it still try and go back to the command speed?