Thanks for the feedback, and for the welcome greeting.
As I think about this more, a larger top might allow one to clamp the jig to the saw table, and not rely purely on the weight.
Or, one could make a larger lip, like Kevin did for his jigs, and clamp it to the front of the table.
Cool jig. If you left more on the left of jig, would the weight not help to make it more stable when cutting larger circles - help with the rocking problem you mentioned?