See if you can try it before buying it, or make sure they'll refund it after a few days if you don't like it.

Then, take a few pictures with even illumination for the subject in the corner(s) with detail you can judge with your eye. For the first picture, don't use any movements, and for the following ones, add some rise/fall or shift. After printing straight from the negatives, compare the corners where you're getting closer to the edge of the circle, and hopefully you'll see how much movement you can get while still getting acceptable results.