I prefer co2 because it's more convenient, both carrying it around and inflation speed/ease.

I've never had more than one flat on a ride, though I carry 3 cartridges just in case, but even with three cartridges and the inflator, it's still smaller than my road morph G, which I just leave at work now. I have a floor pump at home. I've only had to use one co2 in the year or so that I made the switch.