Since you have mentioned it, i have tried to implement a solution. In real life, when you change direction, you get slower. So, getting the inputAxis change rate (difference between previous and this frame), and lowering the Max Walking Speed due to the change rate, combined with a Speed Warping node, gives what you want. No foot sliding when changing direction. I am going to publish a whole project with Blueprints set up in my plugin pages with a Dropbox Link when i am done with my whole system. So, you can also see how i have implemented it.
Edit: Here is what i mean: Direction Rotation Change Speed Decrease - YouTube