Also I have tried the engine failure take-off at V1, the rudder efficiency is not enough to meet Vmca requirement, I have to give some aileron input and bank to keep fly stright, with about 15~25 of drift angle, even when speed are up to V2+10~20.
While CS757 is not designed for failure simultaion, it's quite easy to fix by change the rudder_effciency value in aircraft.cfg then (I use 1.3 but without strict test.