it doesn't matter what your beef starts out as - it's how it ends up.
the scoop on "lean" beef:
http://lowfatcooking.about.com/od/lo...a/leanbeef.htm
now, when it comes to what is going on your plate, here's what happens:
you spend the extra money to get lean or extra lean beef.
you make it into - for the sake of argument - burgers.
you roast them in the oven on a rack.
you need 4 glasses of water to choke them down because they're so dry.
or
you spend less money on regular ground beef
you make them into the same sized patties
you roast them in the oven on a rack so they're not swilling in drippings
you enjoy a moist, delicious burger.
the difference in the moisture content between the two burgers is not the fat - the regular ground burgers are moist because they have not lost as much water as the lean-meat burgers have. when there is a higher fat content, a non-fat cooking method removes fat but the water stays in the meat. the finished product is not a whole lot higher than the lean meat when it comes to fat content.