I strongly believe that a standard "mortar" would easily out-perform and replace the cluster not only by the amount of attention required to shoot and aim, but also putting more power in the heavies hands for both offense and defense. Bottom line is that a classic mortar would serve ALL the same purposes, and take less time to aim being a fire and forget weapon. With the cluster you have the choice of doing super OP dmg to someone and possible lagging half the players on the map or just firing a regular nade....usually with the timing and skill required to effectively use the cluster you barely have any window to kill fast targets.
Same dmg... less time needed to aim.....think about it. NOT BOTH
p.s. you could even go the skybolt direction with it and have TWO mortars, one which is entirely fire and forget and the other which has the timer function that the cluster had but without annoying bullshit particles everywhere but less splash and dmg.
Same dmg... less time needed to aim.....think about it. NOT BOTH

p.s. you could even go the skybolt direction with it and have TWO mortars, one which is entirely fire and forget and the other which has the timer function that the cluster had but without annoying bullshit particles everywhere but less splash and dmg.