I feel obliged to point out that EUREKA ran for five
seasons (which is a decent run in an age when network shows rarely survive their first season) while WH13 is in its fourth
season and is still going strong.
Compare that to, say, TERRA NOVA or ALCATRAZ or FLASHFORWARD or THE EVENT or THE SECRET CIRCLE or AWAKE or DOLLHOUSE or FIREFLY, etc.
I'm not sure where people got the idea that Syfy is quicker to cancel genre shows than anybody else. If anything, it seems to be the other way around . . . .