Just installed 800n opener, took about 3-4 hours, had to weld extension on the pipe and move the door bracket out. Otherwise would have taken less than an hour.
The center hole in the opener is 35mm, I just about didn’t order because someone keeps saying it is 32.
You can wire a wall button to the opener very easily, the connection points are in the manual.
This thing is super quiet, don’t know how long it will last, but I’m loving it for now!