I've given up on CO2 for a couple of reasons. First, you can always have more flats than you have cartridges (I've had nine on a century), and if you have to carry a pump for backup, you might as well leave the carts home. Second, I use big tires (I weigh 240), and some carts won't inflate them fully. If you have to carry a pump to top them off.... I don't like the waste of throwing cartridges away, and I don't like finding them in the woods when I'm riding my mountain bike, and I don't like the cost (I have about 30 flats a year, so it adds up).
Mini-pumps sound good, but I've never found one that worked very well. My Zefal hPx will inflate my 37mm tires in fewer than 100 strokes. The last two minis I tried took 450 and almost 600.