I use CO2 on the commute IN to work, because I'm riding to catch a train, and I'll be waiting for 35 minutes if I miss it. Going home, I use the Road Morph, and save my CO2.

All my MTB buddies use CO2 and Stans or other tubeless goo. I know Stan's dries up over time, but I've never heard of it being instantly congealed by CO2.