Seeing as this thread is still going, I'll go ahead and post some of my own footage / conclusions flying these SLFs at Planetary Port CZs (so... in the absence of Thargon Swarms):
The Javelin and Trident are completely outclassed by the Lance with either an NPC pilot or a player at the controls. The Javelin's DPS is great on paper, but good luck using that beyond 200m with its ridiculous spread (and NPCs struggle with that too, opening up on targets out at 1 km+ with the energy waves flying everywhere); the Trident just doesn't have the projectile velocity nor the DPS for it to be worthwhile, especially against Scouts and exerted hearts. With the Lance, I can challenge Basilisks and win (assuming they don't focus me

) and I can have my NPC pilot wear down the shields of the larger Interceptors while I'm rearming my Cutter's Heatsinks / weapons.
While I personally think the Lance is the best of the bunch, they all share several glaring flaws: receiving the Caustic debuff is an instant wipe, Thargoids have aimbot-level aim even against them and they have no way to run cool to counter that, they crumble quickly due to Phasing damage, their hitboxes are huge, and you have a fraction of a second to dodge Scout missiles at the ranges the Javelin and Trident are effective at, with
zero warning when that happens (especially if the Berserker buffing your target is sitting fat and happy at the port 20+ km away, well off your scanners).
Meanwhile, the AX Taipan is much,
much more robust, with more Hull HP and the same Shield HP as the Guardian SLFs. Its slimmer frontal profile allows it to dodge incoming fire far easier, so much so I can challenge an attacking Interceptor using a corkscrew maneuver without too much worry. Its AX Multicannons are decent, too, offering good DPS for either exerting or destroying hearts. Unfortunately, it shares some of the flaws of the Guardian SLFs, mainly the Caustic Debuff being an instant wipe and the Scout missile problem. NPCs also don't know how to fire the Multicannons, so these are Multicrew only until that bug is patched...
At the very least, I'd like to see all of these SLFs outfitted with Caustic Sinks to deal with the Caustic Debuff issue and mitigate the Scout missiles somewhat. I'd love to see both the Javelin and Trident brought up to the destructive power of the Lance at some point - preferably via a direct, no-nonsense buff,
NOT through re-unlocking them on a per-fighter basis like the Salvation weapons.