denti,
You made me doubt for a second so i opened my FCTM(dated 31/oct 2006).Page 3.26.
It states:<After flaps and slats retraction is complete,select VNAV or set the the desired climb speed in the MCP speed window.Before selecting VNAV,flaps should be retracted because VNAV DOES NOT PROVIDE OVERSPEED PROTECTION FOR THE LEADING EDGE DEVICES>
The vnav would make the aircraft accelerate to 230 kts (5 kts below the overspeed for leading edge devices),remember loss of system B, you are limited to 230 kts as the LED wont retract.(its on speed placard in front of you).
If you are in vnav and enter an increased headwind along with a slow A/T response you will get a slats overspeed....and in todays QAR big brother watch id rather not do it...
Also most NDP require to accelerate to enroute climb after 3000 feet(250 if limited below 10000) and keeping max flaps up speed before that.,so i dont see the point to accelerate with vnav on take off,especially if the aircraft is not fitted with speed intervention.
Anyways bit deep for a VIRTUAL738
regards