As long as you can find one for a good deal, they're great markers. Those and cockers ruled the upper echelon of painball for a long time. Those 2 markers are probably the best mechs that can still be found.
Classic valved mags can take co2 just fine. They might not be the happiest marker alive when using it, but they can use it. I'm not 100% certain, but I think Xvalve mags should only be run on compressed air/n2/hpa.
Ok so i should stick to the Automag 68? The one im looking at it has a response trigger but its oldschool. so when you pull the trigger it will fire a ball then when you let go it will fire a ball then too! I thought that was pretty cool
There are, in fact, Auto Response frames for mags that allow the marker to fire once on the pull and once on the release.
Don't mistake that with the effect of an RT, ReTro, E-Mag, or X-valve, which along with a faster cycling speed, is a 'reactive' trigger that pops back out after every shot.