Oh, the 1Ds. Wow, I thought that camera was only used in the studio.
Why would I switch? I suppose it also has to do with peer pressure. All my friends that are into photography (like me), use Canon...Albeit not fullframe. And it is not as if they have ever said, "Oh, you really must switch to Canon." In fact, we've all talked about how brand loyalty is stupid, and that we should just shoot with what we like, but it is more subtle than that.
Oh, and Nikon just announced a 45mm tilt/shift lens, this month. And a good digital full-frame body, akin to the 5D. So as of right now, both camera makers are more-or-less on par.
I only have my F100, and one lens...So it is not as if I have a huge collection of lenses, or something.
It's not as if all the photographer's I look up to all use Canon or something, most of them use large format, anyway. And the man that taught me photography, that is to say the one photographer I probably have the most respect for, used Nikon. That actually led me to get my F100 in the first place.