I own the GL702VM, it does not have optimus, and will chew the battery in 4 hours, or less than 2 when gaming.
The upside is it includes a 75hz Gsync display, and will game awesomely.
The Asus has better cooling and will probably be more quiet because of it. Plus its a DDR4 based platform, 3.1 Type C port, might have Gsync, dual hdd slots, etc.
If there is a tiny hole, use a paperclip that you bend straight to push in there, try to do it lined up well, not off to the side. May need a good hard push.
I'd make sure it stays on for ten minutes at least, hit up chrome with lots of tabs, try every kb button and wifi, hit the dvd eject button, unplug it and see what the battery does after 5 mins.
With that wear I'd offer $75 at most.