As a rule, I hate 'rule-nazi's'. BUT...prior to V1, the only hands that belong close to the thrust levers (747-400, throttles for piston) are the hands of the person responsible for RTO decision-making (in our case PIC). No back-up before V1 by non-PIC, to prevent ambiguity & interference. If thrust is not set prior to 50 knots, it can be set easily by the PIC (manually); since this situation only occurs at very light weights, in 99.9% of cases it's not critical.
What I HAVE found to be critical is the 400' transition from TOGA mode to VNav; in certain conditions (ie; EEC malfunction with a poorly-written MEL) the thrust can reduce to idle; not very good at 394 tons in hot wx. It does get your attention; if, in addition, you were to experience an engine-out situation, your interest would increase further.