I use the 2nd brightness setting and I get 8-9hrs till the LED turns red, 11-12hrs till it's dead(played Mario 64 DS and Brain Training). I only use Passcard 3 to boot up the G6 then I remove it since it drains the battery.
I received my G6 lite and Passcard3 from Realhotstuff today, they shipped it on 02/08 to middle Europe(airmail letter post). Excellent
I can definitely recommend them.