Tried Beta 18, seems better than all but I notice a bit of slowness while making quick turns....
These betas have nothing to do with right stick turn speed, that's an aim mechanic. These changes are about left stick movement (WASD).
Nor do they account for aim assist, that's a game mechanic. Slower / interpolated strafing speed may help with rotational AA. If movement is more responsive in newer betas, AA may be fractionally reduced, but movement predictability and speed will be improved. The core focus of these betas is to ensure we don't get kicked from Fortnite, not AA.