I've been there and done that.
I went from Canon, to Nikon, and now I'm sticking to Canon - Luckily I kept most of my Canon stuff, otherwise that could have been really expensive.
Here are my 2c:
In brief save your money and don't change over, unless there is a really compelling reason to.
If you feel tempted then rent the stuff a few times before you buy, and rent the whole system (camera, lens, and flash) - One great camera doesn't make a
great system.
I think people swap brands because they start to second guess the initial brand choice they made many years (when they basically knew nothing),
and they start looking at much more expensive (newer) equipment from the other brand, and compare it to their cheap starter kit - who do you think is going to win ?
You can try buy into whatever is the best at the time, but within a very short time-frame the other manufacture will regain the upper hand.
In SA the following has been my experience with Canon vs Nikon.
1. Canon is way cheaper than Nikon in SA (I'm not sure why but just look at the prices of the 5D3 vs D800, here and in the USA).
2. If you are into Sports photography get a Canon with some long L lenses! They are cheaper than Nikon and are just brilliant.
3. Nikon has a more user-friendly flash/speedlite system.
4. Nikon has a very good service centre in Joburg - People are very friendly and it is quite pleasant working with them.
5. I have had to deal with the Nikon Service Centre so many times in the last 10 months that I've lost count :-(
This ranges from: things missing out of my brand new camera box; my software DVDs were also bent; I had to get a dud R10k lens replaced (in the first week); I had to have my WB adjusted twice before they got it right (
http://gordonrudman.com/Articles/6).
6. I have only dealt to Canon SA (CameraTek) once in 7 years, and this was really my fault (I bumped a lens off my table onto a tiled floor) - the service was good but not as good as Nikon.
7. Surprisingly the canon lens above continued to work just fine, but I sent it in just in case.
8. Nikon give free course to beginners (I think canon might be doing this now too).
9. There seem to be some questions about the Nikon Warrantees when selling your kit.
But there is no REAL difference between Canon and Nikon - both make some great kit, if you are willing to pay for it.
Find what feels great in your hands and stick with it.
Using a camera should become like second nature, and you shouldn't even have to think about how to change a setting.
You should be able to adjust all the basic settings without even looking - changing brands will destroy this ability, and slow down your creativity.
Instead of changing cameras, rather spend that money on some great new lenses - it will make a much bigger difference.