I do the mulching of leafs at the end of winter (now-ish) and make sure I do it after some nice dry days so that the leafs are as dry as possible. I use the regular blades on a Toro ZS5000 at the second lowest setting. Indeed, leafs tend to pile up in front of the deck, but they usually get worked underneath the deck, eventually. If not, I set the deck on its highest, position it on top of the pile, and then set the deck to the second lowest position, again.
In dense leaf patches, I go over them 2-3 times.
I do not use any kind of blocker, as I want the mulched leafs to be spread out of the side of the deck, as much as possible.