OS no longer makes a 40LA which is why I mentioned the OS 46LA. You will not have much difference in flight times with BB or Bushed, at least not in my experience.There is more difference in fuel consumption between different brands of engines then there is between Bushed or BB. As to power differences well again that will very between brands.All the major brands have their own websites and here on RCU you can compare engines.Go to User Reviews and click on compare engines. That will provide a wealth of information.