I'm amazed at how difficult many of you are making this. The question is purely about using a high V1 speed when a range of V1 speeds are available and can be used (i.e., the takeoff is not field length limited and multiple V1 speed data are available in the AFM). It says nothing about changing V2, using improved climb, or overspeeds.
Aerocat is spot on. Using a higher V1 results in a shorter accelerate-go (i.e., takeoff) distance, which will also increase your vertical clearance over obstacles. You get that increased vertical clearance because you got into the air in a shorter distance; there isn't any effect on your climb gradient.
Last edited by donstim; 18th Feb 2012 at 19:11.