Nick,
I didn't know the granite would sag...maybe not the best idea then. Also, I have to agree, I do like magnets as well for jigis and fixtures. I guess I'm used to not having that feature on my mdf/formica router table top. I totally forgot about benchdog, but I don't think it fits jointec.. I also want to fit it to the jointec lift which I beleive is a little different size than other router plates. When I went to woodwerks in comlumus a few weeks back, In there back room was a router table, steel cabinet with a cast iron top. It was cut for a router plate. I never got a chance to ask the price or what plate its cut for. Plus I like the cabinet I have.
I thougt I had my mdf top supported but it has sagged almost 1/16 inch center to egde. Maybe I need to take it off and re do the support system. Also when I made the top it is two layers of 3/4 mdf, glued and screwed. I only laminated the top side. Maybe I should have balanced the lamination with formica on both sides?