Took me a while, but I finally realized who would make a great choice for SGU.
He's not new to Stargate, as many of you probably remember him from 2 episodes as Lt. Grogan. He had just recently starred in a CBC comedy called Jpod, which, despite being a great show, was cancelled.
The guy's young, his character in the SG universe would fit right in with SGU. He's a known actor, at least in Canada, and especially to young people. He's a good actor, probably not that busy anymore with Jpod cancelled.
Honest to god, I think he would be perfect casting for Universe and I think or at least hope that TPTB might actually take a look at him for SGU.