What about if you made turrets 100% resistant to the damage type the weapon uses? As long as the enemies don't use that damage type, it should allow you to use "placeable-enemy" just fine, right?

Marathon nerfs the fuel value of wood, coal and other fuels. It should nerf solid fuel as well.
This change adjusts the fuel value in a similar ratio to other fuels, so is balanced in the Marathon world.
To revert this change would make solid fuel twice as strong, and therefore OP.

Isn't solid ...

imajor wrote:5.5 iron plate+1 stone/2 tile for track

That's actually for 4 tiles of distance because each track is 2x2, and the recipe gives 2 as well.

Edit: Oh yeah, and don't forget about throughput comparison. That would be important if the normal belt doesn't cut it.