Sleeper Simulant is an exotic linear fusion rifle that was brought originally in destiny 1, and was re introduced into destiny 2 during the warmind DLC. The whole way the gun functions seems like it would reward some of the highest damage output or damage per second (dps) if you are hitting crits or headshots. The xenophage is an exotic machine gun that can be used for similar tasks as sleeper like boss or raid boss damage, in most tasks the xenphage can out damage the sleeper simulant and you don't need to be hitting critical hits on the enemy making it much easier to use. Another thing you can compare sleeper to is 1000 voices, the 1k can give similar if not better damage than sleeper without hitting headshots not to mention 1k voices is also great for area of effect or splash damage as it shoots an explosive beam and its a fusion rifle as well which too some people is literally a better version of sleeper also to mention sleeper only can mildly complete with its extremely long catalyst grind while these other weapons don't need a catalyst to out perform sleeper. With the sleeper you can still do decent damage with body shots but its heavily out performed by so many other weapons. These guns have something similar which is total damage output letting out all of its ammunition. If bungie buffs the sleepers reserves from 9 and 11 with the catalyst to something more like 12 and 18 with the catalyst or 15 and 18 with the catalyst it would give more of a reason to use the sleeper simulant rather than just letting the weapon catch dust in everyone's vault