with the latest 1.32 software on the ESC I get nothing but cog, as in the motor vibrates slightly when gas is applied. With 1.26 everything works fine....
Its an extremely common issue- any firmware newer than 1.24 can cause terrible cogging, but it doesn't seem to happen for everyone however ( may be dependant on the esc revision, maybe not ). Since there is little to be gained with the later firmware versions ( besides torque control mainly ) I would suggest staying with the last version which works correctly for you.