tubular lower control arms

"Tubular" - anything is the must have today. It used to be "billet aluminum" - anything. It doesn't appear to me that these would be stiffer in aft-fwd bending than factory LCA's with a lower stiffening plate.

Indeed, I don't know why people think they need a plate, but perhaps I need to read more. The LCA's purpose is to locate the lower ball joint. It needs to be stiff in the up-down direction to apply the force of the torsion bar. The strut rod locates the ball joint fwd-aft, so I don't see why the LCA needs to resist fwd-aft bending. Indeed, the bolt bushing allows it to bend fwd-aft anyway, no matter how stiff it is.