We've never cooled a corn snake in our snake keeping days. We keep ours at the ambient temp of our reptile room (and we're in the UK!).
Come the right time of the year, in go the boys and (eventually) out comesome eggs.
We get great clutch sizes and have a 100% hatch rate AND a 100% survival rate (bar one escapee bloodred hatchling when the 09s were tiny which I am assuming has perished by nowbut it hatched, ate and thrived before doing a runner out of our hatchling racking. This season we've paired somewhere around 20 adult females with males and (the OH keeps track of corn breeding not me so i'm not 100% sure) as far as I know we've had mating in every pair so far.
We get decent clutches, healthy hatchlings and even "double clutchers" without brumating our corns.
The corns:
http://masonexotics.co.uk/corns.aspx
The breedings:
http://masonexotics.co.uk/Pairings_2010.aspx