A 700 will use about 1200 meters from start to rotation on a derated take off. You can take off, land and stop safely with a touch of brakes and idle reverse on a 4000 meter runway.
Fl 1 is perfectly safe on both 700 and 800 NGs. The only time I use more is when I am runway limited.
Yes, you get less tail clearance with FL 1, but if you know how to rotate an aircraft, it will never be a problem.