Ignoring for a moment that a large-scale, turn-based table top war game is a terrible thing to use as a comparison for a third-person lobby shooter/melee game, the lascannon on TT is balanced in much the same way. It does very high damage, particularly to vehicles and will one-shot most infantry. But it is a move-or-fire type weapon and only has one shot per turn. Compare that to the heavy bolter which fires 3 shots per turn to fill the anti-infantry role and you'll see the TT lascannon has roughly the same design philosophy as the one I've mentioned above.

Low mobility, high damage tank hunter that CAN be used on infantry but is not really efficient to.

Actually with that twice as fast lock on as normal I could very easily see getting lockons even at medium range. I think you underestimate people's ability to hold a crosshair on a target for a short period of time. I mean look at the OP's video he got a bunch of moving targets at medium range, some of which even saw him and tried to play accordingly not knowing it was a unique LC.

I actually own that gun and i'm talking from experience, if the guy is moving in the open, sure, if you're good enough you can track him, but not if he is moving between covers, because there's a fixed X time you need to keep your tracker on him, with a AC you can take snapshots in between covers, all you need is a split of a second of exposition, with Lascannons, even the Burning Light, you need a minimum time of exposition, and that time is even greater than the AC's TTK.

It is a good bit easier to get locks on the large maps like Harkus and the Imperial Fortress. I don't use it in skirmish because people are too mobile. But on those maps atleast theres tons of spots where you can just exploit.

With the melee system in this game as well if two people are stuck on a clang battle its pretty funny, and if you follow a JPA and start locking him when hes doing a ground slam its also pretty funny sometimes.

All in all the autocannon is much better due to being able to fire whenever. If the lazcannon had it I can't imagine the amount of TK's there would be.

So finally fought against someone using this thing on a fortress map. Holy crap was it annoying. There is almost no way to counter this at range unless other factions have fast charge accurate uniques as well. Luckily I was stacking so much HP on my orks that I could actually survive the hit with about 1% hp left over. This thing would play hell on eldar I bet since they usually wait to the last second to dodge it seems.

I got the Voice of The Emperor Heavy Bolter. No idea what it does but it looks cool.

Also the Vulkan Multi Melta. Does a fair bit more ailment build up than the base melta.