I can drain, measure, refill all at once with the engine cool on the 6R80 and not have to be concerned about running it up to hot and burning my hand and stuff, checking the level in multiple steps?
That would allow me to perform the refill from the top with a funnel and long hose instead of getting underneath with the pump and hook thing.
I would not be doing a pan drop since I had a tranny weld-in bung and drain installed on the the pan at 40K miles when I did the first drain and filter change so I should be able to get all of the fluid in one container for accurate measuring.