Concerning dueling heroes...
First of all, heroes to some extent are generic. There is no personal control over them. Thus, I f I see that his hero has more hitpoints/attack than mine - what is the use of dueling? It would only mean defeat for me, victory for him, and a cool show for those watching.
Unless it could be personalized [a mini-combat rpg system] I think it is an impractical concept.
"Yes... I am writing a book. So far I have the page numbers." - unknown author.