I agree with Denise. Carry the Topeak Morph... no need for anything else.

Used cartridges for awhile. No question they inflate a tire in lickety split but there is room for error and if you used up all your cartridges and tire is still not inflated, you are screwed. I ended up using a pump anyway and so just eliminated the CO2 product I had to carry.

Some people swear by them and carry nothing else. Just know how they work.

They do work on all tires but you may need 1 1/2 - 2 cartridges (depending on size) for MTB tires.