I see youve never had the joy of using a NF gunboat heavy against pubbers and watching them shit themselves :D
I've not used salvo recently but it has its uses, dual he/salvo or dual salvo/he heavies with a fast engine are good at oneshotting turret clusters and doing hit and run damage to poorly laid out bases. Though they are pretty poor for antitank. Also guided was my favourite anti tank ml a few rcs ago combined with a high dps mg. They are still OK but in most situations where you might use it homing is better. I have also been playinv around in the research tree, more often than not its been failing!
Oh god I miss missile boats from 2.12. I remember rushing nothing but completely plain heavies on escort, and clusterfucking the S-bend with 15 5xstdML NF Heavies. Good times. I should re-enable that.
Straight outta' empires/empires/scripts: UML: 60 Damage, 1.0 Cycle Time, 3.8 Reload Time, 6 Clip Size, 6 Clips Salvo: 35 damage, -0.14 Cycle Time, 3.0 Reload Time, 4 Clip Size, 4 Clips Guided: 50 Damage, 1.0 Cycle Time, 6.0 Reload Time, 5 Clip Size, 4 Clips Homing: 45 Damage, 1.0 Cycle Time, 6.0 Reload Time, 6 Clip Size, 6 Clips The negative cycle time for Salvo means it fires all the missiles with a 0.14 second cycle time. So over the course of a full use, UML will do 2160 damage, Salvo will do 560 damage, Guided will do 1000 damage and Homing will do 1620 damage. Over the course of a single clip, UML will do 360 damage, Salvo will do 140 damage, Guided will do 250 damage and Homing will do 270 damage. Now for the real meat, the damage per second. First per clip: UML has 72 DPS, Salvo has 1000 DPS, Guided has 62.5 and Homing has 54. Finally, DPS including reload times: UML has 43 DPS, Salvo has 39 DPS, Guided has 25 DPS and Homing has 25 DPS. Now what does this all mean? Quite simply, if you have time to sit around and fire, UML is better. If you need to get the fuck in and out of Dodge, Salvo is better. There's some specific time value at which UML becomes better than Salvo, but a good estimate would be that if you have time to fire off the whole UML clip, then it's better. Guided and Homing are outright sins compared to UML and even Salvo, unless you really outright suck at aiming.
Oh, and the manual is out of date, so I wouldn't use it as a reference for anything. For example, the vehicle outfit page lists Upgraded Guided and Upgraded Homing missile launchers. The whole thing needs a good updating.
You can't take things based on raw DPS though. Heat per Second is important as well, not to mention that the speed, guidance and homing aspects of the missiles all account for things. If I gave Homing or Guided the same DPS as UML, why would you use UML?