I have a Barbieri that is a combo mini/co2 pump. It's very convenient. I manually pump some air in the tube when remounting and then use the co2 to finish the job. The pump has a built-in gauge so I know when to close the valve and save some air. It uses 16gr cartridges.
It fits in my saddle bag with an extra tube and an extra cartridge (1 is already inside the pump). On long rides such as centuries I add a second extra co2 cartridge and a second tube in the bag.
I only came up short once on a small ride. I didn't check the tire enough before mounting the extra tube and pumping it. A small staple or metal wire piece was still in the tire thread and I quickly flatted again. I still couldn't fing anything in the tire, fixed one of the tubes and used the 2nd co2 cartridge. Well you know the ending... another flat and I was out of co2. That's when the minipump option is convenient but, as mentioned by others, not very efficient. Yet it still allows you to return home.