I love cart vs pump threads!

CO2 is faster, smaller, and lighter - pumps have somewhat of a reliability advantage and no waste.

CO2 doesn't exactly "leak" out of the tubes, it diffuses through the rubber - everyone who uses CO2 knows of this issue but it's unlikely to be a problem so long as you can pump up with air within a day or so.

You guys who play the waste card though - if a couple carts per year would represent a significant increase in your landfill contribution, I salute your commitment to the environment.