This is how I think:
Heatray falls off over range. This implies this turret is a close range turret, since its long range effectiveness is, presumably, very weak.
Thus, it competes with Stardust. Heatray is single target. Thus, it is a short-ranged turret which can only shoot one target.
If it has the same range profile as Stardust, people will make Stardust because that has AoE, and units which like to get close to fire (raiders and assaults) tend to appear in groups, which the heatray, unless it is unbalanced, will have problems dealing with.
Now, it could also compete with Lotus. However, Lotus is cheap, and does not suffer from damage drop off at a distance. So unless this turret is cheap, it will not be worth building over Lotus.
At best, it can deny people rushing in to kill mexes, but Lotus already does that, and a heatray turret is fundamentally the same as Lotus - deal damage to one target, force the enemy to bring more than one raider.
Perhaps this turret is longer-ranged: Then it competes with Stinger. However, Stinger is liked because its immediate damage dissuades going in that area unless the opponent is prepared. A heatray at that distance would not have the same effect. Again, this turret is compared unfavourably to another.
So unless this turret is massively OP, it will suck.
I also say it sucks for a different reason:
Since it is a heatray, this dissuades attempts to rush in (since it deals more damage at close range). Assaults and Raiders (to a lesser extent riots), are affected the most.
This makes best play to use skirmisher and artillery to kill this turret, since rushing in with assaults/raiders will end up with losses, while skirmishers and artillery can harm it with little chance of loss.
Making the turret tanky also makes assaults and raiders less viable, because this gives more time for enemy forces to respond, and the turret time to kill some attacking units. Giving it an armored form just makes artillery and skirmisher a worse answer, and still does not solve the problem of dissuading assaults and raiders. (Like Faraday).
So it directly feeds into Porc-K and Artillery-K by being a turret where rushing it is likely to be unviable in a lot of scenarios (token mobile army, if its cheap enough, heatray forest, strong enough, able to fight multiple assaults, etc).
I
despise Porc-K and Artillery-K.
Zero-K needs less things where 'make artillery' is the answer to it.
This turret does not do that.
So a heatray turret sucks as an idea.
