The only shows SciFi/Syfy has ever cancelled midseason have been reruns it acquired from other networks, like Charlie Jade. (Which means it could theoretically happen with something like Continuum or Primeval: New World.)
Just one point. When Syfy pulled Charlie Jade from prime time, they did continue to air the remaining episodes. Yes,it was at 3:00 AM Tuesday mornings, or something. But they did honor the contract and let them all air. It illustrates once they have paid for something, it will make it to air.