Relating to your statement about how Henderson might have trouble if he's on his back, Henderson is a very strong wrestler and it would be hard to get him on his back. That being said Jones has taken down good wrestler like Ryan Bader.
Shogun Rua isn’t the greatest wrestler and he was able to get him on his back. Granted he was super tired, but still. Jake Shields was able to do the same. Wouldn’t you agree Jon Jones has better takedowns than both of those above? :)