"I don't bother with CO2 because it's a constant expense and remember to buy more when I run low, I have limited air supply, I have empty carts to hassle with, and then have to drain the air out and refill when I get home. I can't be bothered."

Me neither. I have a Topeak Road Morph G. Air is free and unlimited. Pumping is a good cardio workout. I can help other riders and not worry about leaving myself short.