Seems like Volvo was thinking when they offered the optional DRL interrupt switch on the pre 2002 VN series and the low beam flash button as well as marker flash button located on the steering wheel on the 2002+ VN series. Much more convenient than having to turn the 3 position switch back and forth. 8)
A quick high beam flash shouldn't be too blinding as long as you're not staring into the mirror. You shouldn't be staring into the mirror anyways.