I was told type F would tighten it up/ give harder shifts. The transmission shop guy that helped me with mine said if it working right, no reason to use anything but the Dex it was supposed to run.
I agree. The racers started using type F years ago for firmer shifts. Most street cars don't need firmer shifts and if you shift kit your Tflite it will have them with Dexron. My Swinger shifts firm with a little Kickdown adjustment and Dexron.
