I just ordered and received a steal sunstar. Got it from Denniskirk for $27. It would make a good dumbell weight. I would have returned it if I did not have to pay for shipping. A few mfg like sidewinder claim an increase of 2 rear wheel horsepower by using a lighter sprocket. The rear sprocket is both unsprung and rotating, double the effects of extra weight!
So my advice go with a hybrid like sidewinder or an aluminum. Im running my steal at the moment and it feels like I have a flywheel weight. Makes the rear brake feel like its doesnt work too!