I carry CO2 kits on every bike in case I get a flat on group rides. I don't want other folks waiting for me, especially roadie groups -- they'll drop you at every intersection, so getting a flat that takes longer than 15 seconds to fix ensures a solo ride.

Kidding, I stopped riding with groups that have that attitude.

I carry CO2 as a courtesy to friends on group rides, or rides on brutally hot days so I'm not adding to the risk of heat exhaustion by using a pump. But so far I've never used any of my three different CO2 inflators, including a Planet Bike Red Zeppelin and two others I can't remember.

Every inflator will have some negative reviews. Often it's operator error. I've watched other cyclists using inflators incorrectly, or neglecting to check the tire for the thorn, glass, etc, that caused the first flat, then blaming the CO2 kit. So choose one based on detailed informed reviews by experienced cyclists.

Regarding mini-pumps, I have three: the shorty Topeak RaceRocket HP, longer RaceRocket HPX, and longish Blackburn Core Slim. All require 200-300 strokes to reach riding pressure -- not full 100 psi pressure, around 75 psi, enough for most folks to ride carefully with 700x23 tires.

I've heard some folks claim they get full inflation from a mini-pump with only 100 strokes. I smell meadow muffins. I doubt they actually counted their strokes or measured the pressure. I've counted every stroke, every flat, and it never takes less than 200 strokes even with the longer HPX and Core Slim. The shorty HP needs 250-300 strokes. Some mini-pumps have even less capacity per stroke.