My personal fear has always been that colonoscopies or endoscopies might make the scarring of the intestin worse, even though it is needed for the initial biopsy, there is no way around this atm. I completely agree that an MRI does not replace a biopsy for diagnosis.
The "tube" they use for colonoscopies is still quite thick, it has a camera, a light, air pressure tube, something to take the biopsy, it's a thick and quite rigid tube. I had a colonoscopy about 10 years ago and was in horrible pain when they took one, didn't get many painkiller, I wonder if I had gotten any at all, I was literally screaming in the room where they did it, worst pain I ever felt in my life, I wonder about the side-effects of taking a colonoscopy sometimes.