My wife made tamales for my birthday recently. She tried a few tweaks from the usual recipe. One was getting freshly-ground masa from a tortilleria, and the other was rendering our own lard.
The lard we got was probably ground fatback, but was just labeled "lard." We got it at a Mennonite grocery for like $2. Apparently the unrendered, raw fat is commonly called "lard" too. As you render the lard, you get less and less pure lard, and more pork flavor. If you're using the lard for pastries that might be an issue, but for tamales the pork flavor is fine.
The bad thing about using fresh masa is you can't infuse the masa with flavorful broth. It's already about as wet as it needs to be.
Overall, I'd say using fresh lard and fresh masa is maybe 10% better, but if you have to render the lard yourself or grind the masa yourself, it's not worth it, to me.