If I haven't said it already....
On a shelf road (with a cliff to one side, and a steep drop-off to death below) with folks behind you (or on a dark and stormy night with your best girl) is not the time or place to show off your mad tire repairing skills. My idea of a good time is not to spend time on the side of any trail (when we should be moving forward) watching you show off your tire repair skills. Put on the spare, keep going, and then when you stop for the night, THEN show us how good you are with tire irons, patches, bailing wire, etc.
I'm glad some folks out there are good at doing tire repairs. I need to order some spoons and a repair kit (I've taken a class more than once). But this is not a substitute for having a spare tire. Some tires are not repairable.
I have the feeling some folks on this thread are just wanting to argue their point trying to justify not carrying a spare because they've got all the tools and skills to fix a possibly fixable flat tire. Again, not all tires are repairable.
If you don't have a full-size matching spare tire, you're not riding on any trip I'm organizing, and many organized trips require a full-size matching spare tire.