I am looking at a new 3 ball roller. Is the signature worth the extra $ or stick with the rolling thunder?

I got my wife a Signature, and I think it's worth the money, the material makes it MUCH easier to clean than the canvas.  I think it's still the same 5 year warranty as the others, it just doesn't get as dirty and is easier to clean when it does.  However, yes, the only thing that's different is the aesthetics and bag material.