I have had my 2020 dl650 XTA now for 3500 miles and have no real complaints other that the length of the key and how high the panniers are mounted. I just completed a 700 mile trip and with an Air Hawk the seat was fine. I am 5'10" and the feet hit the floor fine. I will say I really don't care if both feet touch as my right foot is on the brake when I stop. I would suggest not to lower this bike it only has 6" of ground clearance and lowering will impede any off pavement usage.
As far as mileage I have averaged 54.76 MPG. This is all types of riding, some dirt two lane pavement highway, etc.best 62.96 worst 45.02 MPG.
The little V twin. has plenty of power FOR MY NEEDS, it handles well and in the grand scheme of things it does everything well and nothing great.