I'm against this purely because altfire was always an avoided concept in the game. Also, consider how broken Spark Shock and Time Stopper would become with this. To elaborate, Time Stopper would guarantee a kill or even two, and Spark Shock would become extremely fucking deadly with an alternation between its projectiles and easy buster shots.
For a lot of other core weapons? Their damage output would rise to insane levels nothing short of v1a Gyro cancelling. If nothing else, this would bring up a lot of balancing issues.