Hydra Laser is a mid-range auto shooter, same sort of niche as the Autogun and Tommy. I use it a lot when I'm bootstrapping myself into the midgame, it's not great (ex. Assault Laser does the same thing but better) but a bad autolaser is still better than no autolaser. As for how the Hydra Laser stacks up against other mid-tier autoshooters...meh? I'd run a gyro-stabilized autogun or a laser tommy over a hydra. Once you've got your choice of lasers and automatics the Hydra Laser falls off firmly into the "mook gun for enemies" category, but when you loot a Hydra off the first Humanist Instructor you kill it's the tightest shit.
For the infantry laser, what's already been said is accurate. Just like it says on the nameplate, it's a shitty lasgun for your infantry. Some laser is better than no laser, right? Same niche as the ol' rifle, hunting rifle and battle rifle, same 'tier' as the battle rifle. That is, a mostly-mobile single shooter for mid to long range that's equally good for kneel-and-aim or move-and-snap fighting styles. Just don't expect to get more than one shot downrange (2 snaps max) per turn.
