Does it take a lot of passes? We have a lot of trees surrounding and in our yard, and the massive silver maple trees in particular, absolutely blanket the yard in leaves. My mulching blades probably manage to pulverize 1/4 to 1/2 the total leaf mass, leaving it in the lawn, but I still end up shooting the remainder into the woods and gardens that surround the property.
Grinding it all into the lawn would shift soil pH and screw with my carefully-managed fertilization plan, but all that can be worked out with a little testing and trial. My mower could easily last another 10+ years, but seeing as I will probably keep this property longer than that, upgrading now might not be the worst thing in the world.
I did price out the mulching deck for my mower, but the stamped pan alone was like $3800. They said to figure over $7k to build that deck from the parts counter, since the mower is out of production now.