To make up $17K on a $247K loan over the remaining 3 years 9 months, you'd have to be, on average, 1.84% better off than remaining fixed.
($17K / 3.75 years = $4,530 pa, $4,530/$247K = 1.84%)
So the question is, are variable interest rates between now and June 2013 likely to average less...