The wonders of Insul-Brite are debatable. I suppose the point of using it in a table protector is to make your entire tabletop one huge hotpad. If you always place a hot pad beneath a hot pot or platter on your table I see absolutely no reason to use Insul-Brite.

I am in the process of making a couple of fitted table coverings (just in the thinking part of the process at the moment until I finish a couple of other projects) and I am planning on using a couple of layers of batting, but that is more for cushioning than the heat protection.