Platter upgrade for VPI MkIV?

I'm hoping some of you can answer these questions. I'm using the non-inverted bearing and a TNT II platter (acrylic/metal?, sandwich). Is the inverted bearing a significant upgrade and is the (new) Classic platter (aluminum/stainless) superior to the Superplatter? Is the inverted bearing a snug fit in the MkIV plinth? My bearing has a flange with 3 holes for small bolts to secure it to the plinth. The inverted bearing has one large nut on the bottom therefore it seems like it would need to fit snuggly in the cutout of the plinth.