The tensile strength of most aftermarket chains, including the EK3D in 520, is better than the stock 530.
With an aluminum rear sprocket, you will lose around 2.2 to 2.4 pounds of rotating mass when switching to 520 from 530.
This is a great place to order from, best price and service, and if they can't get what you want...it doesn't exhist
www.sprocketcenter.com