I am with you on the "flushing", even though that is what most all dealers and "service point's" will do is "flush"...
It is not hard to do it yourself although the tranny holds quite a few quarts, and it can be a little messy on the driveway.
You can get that last quart out by removing the dust pan off the bottom of the tranny, and using a large blade screw driver, turn the transmission fly wheel and the last last quart will come out of the torque converter.
I just don't don't trust dealers...When they pay their employees $7 to $8 dollars an hour, you get what you pay for.........