Alex,
The EPR is the same but the amount of thrust available at V1/Vr/V2 is greater, your accelerate go/ accelerate stop distances are therefore less.
SR71,
Remind me of your email and i will send you a presenation on the subject.
Slim, Mr Boeing states...
Standard Takeoff Speeds.
V1/VR/V2 should be obtained from the FMS or QRH based on the Actual Aircraft weight and the assumed temperature used for thrust setting. VMCG must be based on OAT.
Optimized V1 or Improved Climb
Speeds must be obtained either from a takeoff analysis for a specific runway or a real time calculation, ie, BLT.
So they are happy for you to use both methods, the decision then rests with how you actually want to do it.
Cheers
Mutt.