I'm not sure what light engine they are using but with the constant updates in technology, chances are it's not the latest and greatest. However, L&M does a very good job with tuning the reflectors to put the light where you want it. So you could replace the LED but it might not work as well with the stock reflector.
Also, they aren't driving it all that hard in order to get decent run times with a 3 cell pack. With a full 1A current driver, you would increase the output at the expense of run time.