I use mods, so take the following with a grain of salt...
I did a number of tests between phase lances with HSA and ion pulsers with extended magazines. In every scenario that involved destroying enemy ships, the ion pulsar outperformed in almost every fight. The only thing phase lances have going for it is that their long cooldown between shots makes them unbeatably flux efficient, I've found that I can spend more time facing down cruisers and capitols in a fight using phase lances before needing to back away to vent. However, ion pulsers make up for their poor flux efficiency with DPS and the fact they can EMP weapons and engines.
AI even handles ion pulsers better than HSA phase lances. I created two different aurora cruisers, one with ammo charges (extended magazines) and one with beams (HSA). I used nexerelin to keep track on damage inflicted. Even when equipped with small rift beams from [super redacted] and phase lances, the beam aurora couldn't keep up with the one using 3 ion pulsers and 4 IR pulse lasers. It kept getting outranged and outDPS'd.
And I'm not gonna lie, I hate that I find HSA to be more of a detriment. I like the concept of beam weapons. Phase and tachyon lances are very good at moderating your flux generation so you don't spend a good portion of your battles running away to vent, but the drawback of having a greatly diminished range in exchange for making beams do hard flux doesn't seem worth it. And the worst part is that you kinda need HSA to make beams even remotely threatening since soft flux is easy to remove.