I did the test with cruise vs rapid heavies in serpentis rock havens.
The fit :
[Rattlesnake, Anom RS]
Ballistic Control System II
Ballistic Control System II
Ballistic Control System II
Drone Damage Amplifier II
Drone Damage Amplifier II
Drone Damage Amplifier II
Large Shield Booster II
Omnidirectional Tracking Link II, Optimal Range Script
Omnidirectional Tracking Link II, Tracking Speed Script
Thermal Dissipation Field II
Kinetic Deflection Field II
Missile Guidance Computer II, Missile Range Script
Missile Guidance Computer II, Missile Range Script
Rapid Heavy Missile Launcher II, Scourge Fury Heavy Missile
Rapid Heavy Missile Launcher II, Scourge Fury Heavy Missile
Rapid Heavy Missile Launcher II, Scourge Fury Heavy Missile
Rapid Heavy Missile Launcher II, Scourge Fury Heavy Missile
Rapid Heavy Missile Launcher II, Scourge Fury Heavy Missile
Drone Link Augmentor II
Large Bay Loading Accelerator II
Large Anti-Thermal Screen Reinforcer I
[Empty Rig slot]
Warden II x2
For cruise setup i used t2 cruise launchers and missile precision scripts in both guidance computers.
The implants :
5% cruise damage, 5% velocity, 5% rof, 5% explosion velocity and 5% for radius (cruise setup had a little advantage here damage wise)
The completion times :
RS 1465dps RHML @ 70km - 17 min 25 sec (965 missiles launched)
RS 1375dps cruise @ 70km - 17 min 17 sec (450 missiles launched)
Time wise they are almost the same (i had more damps with cruise, but i dont care), ammo wise the cruise setup is cheaper. Overall the cruise setup is a little bit better, but both are viable.