JoeW wrote in post #11502370
If Nikon had made incremental improvements over the D100, they'd be out of business by now. Some years Canon products are better. Some years Nikon products are better. I really can't believe that either is so much better than the other that it would be worth a switch. The large investment is in lenses and both companies make nice lenses.
Yes, people do switch, I know several who have, most, but not all, go from Canon to Nikon these days. They sell their Canon lenses and cameras and jump ship. I don't think I would because I don't feel the need to chase every camera review and buy the latest "Best Camera." It does happen and Canon can't be happy to see their market share slip year after year. I know several Pros that go back and forth, owning Canons for a while then selling it all and going Nikon then back again. Keep in mind that many pros lease equipment or use company owned equipment that gets rotated out on a regular basis, they don't own it like you or I would. That way they have the flexibility to change Cameras and gear on a regular basis.
To your second point, no, there really isn't that much difference. If I showed you a picture could you tell what camera it was taken with, without looking at the metadata? Probably not, I couldn't. Nearly all modern cameras produce excellent images, more than worthy of glossy magazines, never mind a web page. But none the less, people do switch over perceived differences. It's a totally different question as to whether or not it's smart or wise, but people definitely do.