So I've done a bit of flying in groupfights with the missiles and the railguns.
-Railguns are probably the best addon weapon. They suck a lot of core but make up for it with incredible velocity and damage. 1000 damage at 900ms is wild, for reference to those that do not know, 1000 damage is what the HEIMDALL 1.00s did last patch. Mixing them with current HEIMDALLs which do a little less than 1000 now makes for a seriously powerful sniping setup. Diamondbacks also mix very well.
-Missiles, I think overall these all should be doing a bit more damage than they are currently. With tracking being all over the place in comparison to Crossfire these missiles really cater to more experienced players to make them work. If your movement isn't dialed in, you're gaining nothing from using any missiles currently. I would amp the damage across the board but make them CDable with the exception of say cannonballs.
Now with that said, these things are an HF pilots dream, on HFs these enable you to explicitly focus on orbiting your opponent and pressing a button once a pass. The pressure output even with the amount of shots missed is still enabling to the point of a significant advantage if you know what you're doing.
In my opinion, if we're gonna be using missiles - we should be going all in with them. Debs and hullbusters are still overall stronger when it comes to VHF to VHF, HF to HF missiles /can/ compete but only among the really experienced pvpers. A new guy would just get wiped if he decided to use these. You can see in the video above from crossfire just how important missiles can be. It doesn't have to go to the extreme of dropping your entire healthbar (this is because of mighty god-ascending holy grail giga-chad starkillers) but if I run a paralyzer and a firestalker and connect both on hull I should see like 40% of his/her health drop down. With dual firestalkers the reward is up there but the risk from CDs is also there.
Tracking wise, you can see in this video, when someone fires those things at you - they are going to hit you unless you know what you're doing. This might sound chaotic to the average player, but if anything this will work to the average players advantage even more - because it will guarantee them some damage in the end as opposed to not being able to hit anything.