I would imagine the lower your bodyfat %, the better the results, However only to the extent if someones really overweight rather than in shape. I.e for instance there would be only slight differences if someone at 15% bodyfat would cut to around 12% etc, rather than someone cutting from 30% to 20% etc.
Im currently approximatly 18% bodyfat, & im still cutting, But only because i know that i'll look better after surgery at a lower bodyfat, & because i want a six pack! ha ha GREED!
but seriously, i personally think itll make little difference if you're already at a low bf%, but if you want to look better after surgery, which i suspect you will, then you might aswell go for it!