Direct fire hellbores? Aren't they direct fire already? You aim, you shoot and the shot races toward the target and either hits or doesn't. Am I missing something?
The standard Hellbore wraps around the ship and implodes doing a disproportional amount of its damage on the weakest shield. The "direct fire" (I don't recall if that is the proper name) Hellbore does damage to the facing shield only. I don't recall how that affected the damage done or hit probability
What drone types did SFB have that aren't present in OP? As for X weapons--what does OP lack in comparison with SFB?
There were several types and the ability to modify them as well. For example in SFB one battle I won because my otherwise standard drones had the warhead reduced to half and extra armor added. Three of them got through the phaser fire that was assured to destroy the 6 standard drones they were assumed to be. Klingons also used warheadless over armored "slug drones" to bring down ESGs.
I believe it was the Kzin who replaced the war head with a one shot Phaser (3 or 2 only I think). 6 Phaser II drones firing from just outside ADD range could make all the difference between the shield falling on the battle pass and staying up. (This may have been the Swordfish drone I'm not sure.)
There was another that was optimized to get some of its damage past the shield even if the shield was still up.
There were also half sized drones (doubled rack capacity) that couldn't hurt a ship but were made to shoot down fighters. 12 of them could be loaded into a scatterpack or you could load 6 and your opponent would likely waste firepower shooting them down when they could not even affect his ship.
There may well have been more but that is what I recall off hand.