I'd only count one of those as a good reason to go Canon over Nikon. Canon's IS is equivalent to Nikon's VR (Image Stabilisation / Vibration Reduction); I don't know what sort of comparison can be drawn in terms of quality of the tech, or the range of lenses that have it available. (I can find info about Canon's lens lineup very easily, but I have no idea where to look to find out about Nikon's current lineup.) [Edit: just saw the earlier post in more depth. Don't worry about the extent of how many lenses the two companies have in IS or VR - worry about whether the lenses you want have it.]
DO is overrated. There are only two diffractive optics lenses available from Canon at this time: the 400mm f/4L, and the 70-300mm f/4.5-5.6 DO IS USM. Of those, the only one I'd seriously consider owning is the 400mm, and at over ten grand Australian, I can't justify the cost. If DO is as good as some people claim it is, why hasn't Canon brought out more lenses that use it?
That leaves full frame. Very nice to have, but by no means essential - right now, I'm saving up for lenses so I can switch over to a full frame (the 24-105mm f/4L IS will do the job nicely, unless they bring out a 24-70mm f/2.8L IS before I've finished saving), but to be completely honest, I can live without it. It's a long term goal, rather than a short term need. And given that full frame bodies start at $AU3000 (or more), well ...
Yes, I shoot Canon, but I dislike seeing differences overhyped as advantages, no matter which system those differences might promote.