I personally don't like CO2 unless I was racing then I would use it because it's faster. But with CO2 you have limited air supply, and sure you could carry a pump to supplement but why? Why carry the weight of both around? Also with CO2 when you get home after filling your tire with CO you have to let all the air out and refill with pump air because CO bleeds through butyl tubes faster then regular air. So now where is you time savings? Plus when you use CO you have to remember to restock your seatbag before your next ride which may mean a quick ride to Walmart to buy more carts. Some of todays mini pumps can reach over 120psi without Herculian effort. The mini pumps attach with special brackets to your water bottle cage so there is no possible way to damage your CF or other frame material.
Barbieri makes a new mini out of TI and it's rated to 140psi and yet weighs only 72grms; Topeak Morph is rated to 160 but it's quite a bit heavier at 270grms. I never exceed 100psi in my tires anyway so the Torelli Aria is all I use which is the lightest and smallest mini pump on the market.