Balls screws ? trapezoid screws? or timing belt ? the more friction you have to overcome the more power you need.
personally I'd feel better with a larger motor, 3Nm sounds a lot better.

As regards graphs, they do give a lot of information IF and that's a big IF you KNOW that graph refers to that particular model of motor. I'm very sceptical on what gets released from China as regards what it applies to.

Like those test sheets issued with rotary tables and the like , everyone passes with the exact same results ?