I've got one of the chargers. I thought it would be great for bringing kegs to parties, but after burning through five cartridges dispensing one corny, my enthusiasm waned. Furthermore, the pressure is entirely unregulated and sooner or later somebody will pull the trigger too many times and blow your cobra tap right off...instant beer shower!
Now I've got three Co2 tank/regulator combos, so I just bring one along. I also bring the mini-charger, just as a backup.
Picnic taps work fine. Just make sure you have at least six feet of hose to prevent foaming. Skip the Co2 cartridge charger though, it's not a long-term use kind of solution. In fact, it's a pretty mediocre short-term solution!