Brent,
I lived in China for several of the past few years, and traveled extensively with my camera gear. I don't think you'll have any problem as long as your bag isn't too much bigger than a standard roll-aboard suitcase. What you'll witness are lots of people taking things/packages on board the plane that, size wise, would not be allowed in North America or Europe. In short, if you can get it from Canada to China, you'll be fine for internal travel.
But, if you are still concerned, or don't want to worry about overhead speace is available or not, I would recommend purchasing a first or business class ticket. In general these aren't much more expensive than an economy class ticket (maybe $100 each way), and it is much more comfortable with more overhead space.
A few suggestions: Jiuzhaigou is a one hour flight from Chengdu, and is the most beautiful place I ever visited in China (I did a big write up on it in this forum). And, while in Beijing head over to the Photo Market by Wukesong (West Fourth Ring Road just north of JinGouHe Bridge). You'll have a great time walking throughout the market and seeing all the second hand shops.
Have a great trip!
Jeff