I'm a pro (not necessarily in terms of quality, but 100% of my income comes from photography), NPS member (not a big deal, just that I've proved to Nikon that I'm a pro and spent enough money on their stuff), and obviously shoot on Nikon equipment. That said, why would you want to join the dark side?

I shoot architecture and portraiture (I don't have much interest in architecture and am making the transition). I don't take video, I don't do sports/action. I only do travel photography for myself, I don't understand the genre of street photography (doesn't mean it's not a great art form--I just don't get it and it's not for me), live in an area with too much light pollution to get shots of the moon, let alone the milky way. I do landscapes if it's in line with architecture and if I'm paid for it (so many people are doing it--there's no way I think I can differentiate myself from people who do it).

So all we have in common is architecture.

If I was strictly an architecture photographer, I'd make the switch to Canon. Only Canon has a 17mm t/s lens. I have a 24mm Nikon, but sometimes it's not wide enough and have to switch to my 17-35 and mess with it in photoshop.

I think Nikon camera bodies have a slight edge over Canon in terms of sensor quality (dynamic range). And Nikon shutter release buttons feel better, in my opinion (most of the time, I'm pressing a shutter release on my iPad while shooting tethered or a wireless release when I photograph children).

Except for the 14-24 f/2.8, I think Canon lenses are better than Nikon over the entire range. And Canon has a bigger selection of lenses (including the 17mm t/s).

Personally, I see no reason to switch unless you have a generous friend with a bunch of Nikon glass you can borrow.