The HIL seems more recognizable based on the color it already has.
i honestly disagree. even if the color of HIL and GB aren't exactly the same, they are still quite similar. in a battle where you don't have the two different beams right next to each other for comparison, have zoomed out a bit, and aren't focusing your attention on one beam the entire time, it can be very difficult to tell which beam is hitting you without looking at the weapon itself.
and HIL and GB in particular are problematic because their effects (and consequently, the appropriate response to being hit by them) are pretty much the opposite of each other: GB is low flux, low threat kinetic damage that is only really useful for putting some continuous soft flux on shields and can usually be ignored entirely when it's just hitting armor. HIL on the other hand is high flux, high threat HE damage that absolutely needs to be blocked by shields and will rip through most armor within seconds.
i remember at least one time where i actually decided to ignore a GB rather than taking the soft flux damage to shields, and then got confused a few seconds later, wondering where the hell my armor went... since that time, i've made sure to always check the weapon itself when i'm hit with a blue beam (at least if i don't already know for certain which loadouts my enemies are using). ^^
try telling at a glance which of these is which:
i find it quite difficult (without staring at them for several seconds). and that's despite having them all neatly lined up right next to each other for easy comparison, without anything else going on in the picture.
as Cycerin said, changing beam colors to make them more easily differentiable doesn't need to involve changing every beam to a color specific to its damage type. but giving the HIL a bright red or orange color would make it easily distinguishable at a glance.
for new players especially, even if they'd be able to distinguish GB and HIL, this could be helpful. after having fought a few battles against ships with GBs, they might not think about checking whether this beam that's currently hitting them is something completely different because it's got a slightly different shade of blue than the ones they've seen before. being hit with a large red/orange beam for the first time probably would tell them it might be a good idea to figure out where it is coming from and what it does.
also, i think it would actually just fit better with the high-dps HE concept; even if the color used isn't the exact same as ballistic HE projectiles, red/orange still feels more..
explodey, to me. ^^