Three good points.
Soft grade plastic weighs less than salt water grade plastic which is denser and heavier. I stay with medium soft or soft plastic when pouring pan fish lures and mix medium-soft with salt water grade for much larger bass lures for the best lure action where lure weight difference is significant. But regardless the grade used, it's not as if your casting 6-10" lures for pan fish. At most I would imagine your lures are less than 3" in length and rigged on jigheads weighing less than 1/8 oz. When it comes to retrieve speed, there's not much difference between 1/16 and 1/32 jigs using the same small lure and no difference under a float.
Many don't realize the weight of a soft plastic lure contributes big time to casting distance yet it's the plastic's buoyancy along with a line's diameter/ buoyancy that reduces swim speed and the distance from the surface given a certain speed of retrieve.
(Flakes do not add weight to plastics but salt added would. Gary Yamamoto's grubs are heavier for example because of an additive.)