First HPA system for me as well - going from CO2 to air was like night and day. No more massive cloud burst, no erratic velocity, no need for anti-syphon tanks and expansion chambers and coiled hose and so much easier to fill. That first Air America Unireg system was the best thing I ever purchased - can still remember the smug feeling as we breezed through a winter tournament without a single hiccup from our Automags, while every other team struggled trying to fill frozen CO2 bottles and tried to avoid drawing liquid into their valves.