AeroTech,
For the regulatory Authoroties that I have done Performance work for, a roll-on takeoff (with minimum 10 knots) is considered as equivalent to a standing takeoff
Beware that this might not be acceptable to all regulatory authorities (It was so in Australia for 3 types submitted to them). Douglas (in the pre-McD days allowed this for the DC9).
The takeoff roll increased (60m or 200ft) for the rolling takeoff was type specific for a Bombardier product that I did work for. It may differ for other aircraft. Essentially the 60M/200 ft penalty was the delta between Standing Start and Rolling Start total distance, the actual distance to achieve Full Takeoff thrust would exceed 60M/200 ft, but at this point, some reasonable speed would already exist.
Boeing's statement that there is negligible difference (less than 50ft) regarding the takeoff roll between the standing takeoff and the rolling takeoff is rather brave. If the takeoff is NOT Field limited, the penalty would be zero. If Field limited (particularly with a Tail-wind) the penalty can be up to 5% of RTOW (That's a 15000 Kg penalty for a B777-300ER).
All AFM scheduled performance is based upon the Standing Start, and that is what I provided when producing RTOWs. As The Rolling start is operationally preferred, I added an RTOW correction at the bottom of each column on RTOWs produced. As stated before, many times it was Zero (long runways), but up to 5% of RTOW when the Takeoff was Field limited (particularly in Tail-winds). In extreme cases, the Standing Start was mandatory, with Rolling start prohibited!
Best Regards,
Old Smokey