In fact it's not inspirated in Deadly Reflex since wasn't this mod who implemented decapitation in games, but still it's a good thing to have in Skyrim, adds more realism.
Deadly Reflex also didn't invent controlled shield bashing, but I'd still dare say that Bethesda considered adding the shield bashing move after seeing how well that worked in the mod.
After all, the reduced backpedalling speed and more powerful archery were also said to be inspired by Dukepatrick's Combat Archery mod.