What's large to you? I can make great quality prints from all kinds of camera. Print quality often has more to do with proper exposure and processing than the camera you're using. A better camera is always nice. But be careful about buying into the hype when it comes to cameras.
One reason to change cameras is marketing. As sad as it is, having a camera that impresses a client can secure jobs. I have a friend who shot weddings with a Hasselblad for just that reason. He didn't love the Hasselblad but his clients thought it was better. The Canon EOS 5D Mark II is a great camera. But you could argue that its reputation is even better than it is. Same goes for the Nikon D700 or D3 - they're both great cameras. But they're never any better than the photographer who uses them. You could very well be making better photos with your Olympus than a super pro with a D700.