I've wondered about this two. My female is around 600-650 grams (haven't been able to weigh her in a while), and she eats a small rat a week, with no problems.

My two adult males, around 1400g and 1300g both eat small rats.
I've wondered if I should bump them up to mediums, since they have no problems with small ones.
Is there anything wrong with feeding medium rats?