FWIW, I have a cheapo pep boys compressor (use as backup), I have an ARB off road compressor, & I have a home built 10lb CO2 tank.

From my experiences...
Versus a decent 12V compressor a CO2 setup will cost more but you pay that over time. Versus a normal pep boys compressor you pay more but the convenience of a quicker fill up may be well worth it.

Compressors
<img src="/forums/images/graemlins/kewl.gif" alt="" /> My $200 ARB compressor can air up 2-3 sets of 33" tires before shutting off.
<img src="/forums/images/graemlins/kewl.gif" alt="" /> This provides some time to talk with your buddies at the end of the trail and relive some of the day over again.
<img src="/forums/images/graemlins/kewl.gif" alt="" /> My ARB would probably cut that time in half (15psi to 32psi) but it just
<img src="/forums/images/graemlins/frown.gif" alt="" /> ARB compressors do fail over time.
<img src="/forums/images/graemlins/kewl.gif" alt="" /> But the wear item is a $2 reservoir O ring <img src="/forums/images/graemlins/cyclops.gif" alt="" />.
<img src="/forums/images/graemlins/frown.gif" alt="" /> A compressor cost a bit more (up front) unless you buy a $20-40 cheapy.
<img src="/forums/images/graemlins/frown.gif" alt="" /> Cheaper compressors may overheat and shut themselves off (if they have built in thermal protection) when airing up one set of tires or more.
<img src="/forums/images/graemlins/zombie.gif" alt="" /> Worse yet, some really cheap compressors don't have thermal shut off's. <img src="/forums/images/graemlins/scared.gif" alt="" />
<img src="/forums/images/graemlins/frown.gif" alt="" /> My $40 cheapy compressor (pep boys) was able to air up my 4 33's but would shut off when trying to air up 2 sets.
<img src="/forums/images/graemlins/frown.gif" alt="" /> My $40 cheapy compressor would take probably 20 minutes per tire (15-32 psi)

CO2
<img src="/forums/images/graemlins/kewl.gif" alt="" /> CO2 uses Liquid CO2 purchased usually at a welding or beverage supplier. Beverage place being the least expensive.
<img src="/forums/images/graemlins/kewl.gif" alt="" /> A CO2 setup doesn't have any possible overheat problem.
<img src="/forums/images/graemlins/kewl.gif" alt="" /> CO2 setup will fill a tire in less than a minute.
<img src="/forums/images/graemlins/frown.gif" alt="" /> A CO2 setup does have a potential hose freeze problem. When the liquid CO2 turns into a CO2 gas, the reaction is EXOTHERMIC and absorbs energy turning objects immediately around it cold. With a cheap poly/plastic hoses (yellow ones), there may be a potential that it will freeze, become brittle, and break. With Urethane hoses, they seem to handle the cold freezes better (still plyable).
<img src="/forums/images/graemlins/frown.gif" alt="" /> CO2 setup will require a bottle, regulator, associated meters, & constant refills at $9 or more per refill
<img src="/forums/images/graemlins/frown.gif" alt="" /> If you run out of CO2, you're done until you can refill the bottle & sources for more CO2 aren't readily available on the trail or even at nearby towns.
<img src="/forums/images/graemlins/frown.gif" alt="" /> A leaking CO2 bottle can obviously kill you by displacing the oxygen. <img src="/forums/images/graemlins/zombie.gif" alt="" />
HTH <img src="/forums/images/graemlins/patriot.gif" alt="" />