Yeah I wondered that about Primal Fear myself. In fact, their drummer Randy Black is Canadian, he was raised in Edmonton and nearly every metalhead in the city knows who he is and the band he plays for, he's a local legend here.
I know that Blind Guardian and Iced Earth had extremely good shows in my area when they did their first cross-canada tours a couple years back, Iced Earth put about 1,000 people in a room in Calgary on their first go around, on their second they sold out in both Edmonton and Calgary with Symphony X, thought the venues were slightly smaller. Blind Guardian sold out a 700-person club in Edmonton and they booked an even bigger room for Calgary because ticket sales were going so well, I heard turnout was close to 900. Hell, Sonata Arctica comes through Canada very regularly in the past 5 years and always sells out (or close) in Edmonton.
Edguy did between 250-300 people here, Hammerfall not quite as much (a little surprised there) and Stratovarius was 150-200, but that didn't surprise me. Dragonforce was just here last month, but they played a smaller venue than last time. Kamlot and Rhapsody have never come through interior Canada, I don't think they've even done Vancouver, but maybe I'm mistaken.
That's all the examples I can give for power metal. Sounds like our turnouts tend to be better than many of the US examples I see here, but bands didn't start touring through here until about 5 years ago, I think Sonata Arctica was the first to come through I believe. We rarely get any of the great traditional metal, Saxon has never bothered. Manilla Road will play their first Canadian gig in Calgary in September.