So they're probably good enough for you!
Canon USA sent out a press release talking about how the 5D Mark II & 7D were used to film stunt sequences on the somewhat popular Avengers movie that just came out.
With intense action and visual effects captured by the Canon cameras, “Marvel's The Avengers” required close-quarter action work with unrepeatable stunts. “The 5D Mark II and the 7D digital SLR cameras produce excellent, cinema-worthy images. They are great for shooting additional angles that give film editors more options for creating powerfully immersive and kaleidoscopic views of action scenes,” explained the film's cinematographer, Seamus McGarvey.
You can read the whole press release here.